Merge release 1.0.0 into stable branchHEADstable

See the tag 'v1.0.0' or the changelog for more information about this
release.

16 files changed, 1289 insertions, 635 deletions

diff --git a/src/main/java/sevenUnitsGUI/DefaultPrefixRepetitionRule.java b/src/main/java/sevenUnitsGUI/DefaultPrefixRepetitionRule.java
index 1fb2709..0e38c67 100644
--- a/src/main/java/sevenUnitsGUI/DefaultPrefixRepetitionRule.java
+++ b/src/main/java/sevenUnitsGUI/DefaultPrefixRepetitionRule.java
@@ -1,5 +1,18 @@
 /**
- * @since 2020-08-26
+ * Copyright (C) 2020, 2022, 2024, 2025 Adrien Hopkins
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 package sevenUnitsGUI;
 
@@ -13,14 +26,17 @@ import sevenUnits.unit.UnitPrefix;
  * A rule that specifies whether prefix repetition is allowed
  *
  * @since 2020-08-26
+ * @since v0.3.0
  */
 public enum DefaultPrefixRepetitionRule implements Predicate<List<UnitPrefix>> {
+	/** Prefix repetition is never allowed; only one prefix may be used. */
 	NO_REPETITION {
 		@Override
 		public boolean test(List<UnitPrefix> prefixes) {
 			return prefixes.size() <= 1;
 		}
 	},
+	/** Prefix repetition is always allowed, without restrictions. */
 	NO_RESTRICTION {
 		@Override
 		public boolean test(List<UnitPrefix> prefixes) {
@@ -40,7 +56,7 @@ public enum DefaultPrefixRepetitionRule implements Predicate<List<UnitPrefix>> {
 			final boolean magnifying;
 			if (prefixes.isEmpty())
 				return true;
-			else if (prefixes.get(0).getMultiplier() > 1) {
+			if (prefixes.get(0).getMultiplier() > 1) {
 				magnifying = true;
 			} else {
 				magnifying = false;
@@ -52,15 +68,14 @@ public enum DefaultPrefixRepetitionRule implements Predicate<List<UnitPrefix>> {
 			if (!Metric.DECIMAL_PREFIXES.contains(prefixes.get(0)))
 				return NO_REPETITION.test(prefixes);
 
-			int part = 0; // 0=yotta/yoctos, 1=kilo-zetta/milli-zepto,
+			var part = 0; // 0=yotta/yoctos, 1=kilo-zetta/milli-zepto,
 								// 2=deka,hecto,deci,centi
 
 			for (final UnitPrefix prefix : prefixes) {
 				// check that the current prefix is metric and appropriately
 				// magnifying/reducing
-				if (!Metric.DECIMAL_PREFIXES.contains(prefix))
-					return false;
-				if (magnifying != prefix.getMultiplier() > 1)
+				if (!Metric.DECIMAL_PREFIXES.contains(prefix)
+						|| (magnifying != prefix.getMultiplier() > 1))
 					return false;
 
 				// check if the current prefix is correct
diff --git a/src/main/java/sevenUnitsGUI/DelegateListModel.java b/src/main/java/sevenUnitsGUI/DelegateListModel.java
index 798383b..da4f978 100644
--- a/src/main/java/sevenUnitsGUI/DelegateListModel.java
+++ b/src/main/java/sevenUnitsGUI/DelegateListModel.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2018 Adrien Hopkins
+ * Copyright (C) 2018, 2022, 2024 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -31,7 +31,7 @@ import javax.swing.AbstractListModel;
  * the delegated list's methods because the delegate methods handle updating the
  * list.
  * </p>
- * 
+ *
  * @author Adrien Hopkins
  * @since 2019-01-14
  * @since v0.1.0
@@ -46,7 +46,7 @@ final class DelegateListModel<E> extends AbstractListModel<E>
 
 	/**
 	 * The list that this model is a delegate to.
-	 * 
+	 *
 	 * @since 2019-01-14
 	 * @since v0.1.0
 	 */
@@ -54,8 +54,9 @@ final class DelegateListModel<E> extends AbstractListModel<E>
 
 	/**
 	 * Creates an empty {@code DelegateListModel}.
-	 * 
+	 *
 	 * @since 2019-04-13
+	 * @since v0.2.0
 	 */
 	public DelegateListModel() {
 		this(new ArrayList<>());
@@ -63,7 +64,7 @@ final class DelegateListModel<E> extends AbstractListModel<E>
 
 	/**
 	 * Creates the {@code DelegateListModel}.
-	 * 
+	 *
 	 * @param delegate list to delegate
 	 * @since 2019-01-14
 	 * @since v0.1.0
@@ -74,8 +75,8 @@ final class DelegateListModel<E> extends AbstractListModel<E>
 
 	@Override
 	public boolean add(final E element) {
-		final int index = this.delegate.size();
-		final boolean success = this.delegate.add(element);
+		final var index = this.delegate.size();
+		final var success = this.delegate.add(element);
 		this.fireIntervalAdded(this, index, index);
 		return success;
 	}
@@ -88,7 +89,7 @@ final class DelegateListModel<E> extends AbstractListModel<E>
 
 	@Override
 	public boolean addAll(final Collection<? extends E> c) {
-		boolean changed = false;
+		var changed = false;
 		for (final E e : c) {
 			if (this.add(e)) {
 				changed = true;
@@ -108,7 +109,7 @@ final class DelegateListModel<E> extends AbstractListModel<E>
 
 	@Override
 	public void clear() {
-		final int oldSize = this.delegate.size();
+		final var oldSize = this.delegate.size();
 		this.delegate.clear();
 		if (oldSize >= 1) {
 			this.fireIntervalRemoved(this, 0, oldSize - 1);
@@ -176,7 +177,7 @@ final class DelegateListModel<E> extends AbstractListModel<E>
 
 	@Override
 	public E remove(final int index) {
-		final E returnValue = this.delegate.get(index);
+		final var returnValue = this.delegate.get(index);
 		this.delegate.remove(index);
 		this.fireIntervalRemoved(this, index, index);
 		return returnValue;
@@ -184,15 +185,15 @@ final class DelegateListModel<E> extends AbstractListModel<E>
 
 	@Override
 	public boolean remove(final Object o) {
-		final int index = this.delegate.indexOf(o);
-		final boolean returnValue = this.delegate.remove(o);
+		final var index = this.delegate.indexOf(o);
+		final var returnValue = this.delegate.remove(o);
 		this.fireIntervalRemoved(this, index, index);
 		return returnValue;
 	}
 
 	@Override
 	public boolean removeAll(final Collection<?> c) {
-		boolean changed = false;
+		var changed = false;
 		for (final Object e : c) {
 			if (this.remove(e)) {
 				changed = true;
@@ -203,15 +204,15 @@ final class DelegateListModel<E> extends AbstractListModel<E>
 
 	@Override
 	public boolean retainAll(final Collection<?> c) {
-		final int oldSize = this.size();
-		final boolean returnValue = this.delegate.retainAll(c);
+		final var oldSize = this.size();
+		final var returnValue = this.delegate.retainAll(c);
 		this.fireIntervalRemoved(this, this.size(), oldSize - 1);
 		return returnValue;
 	}
 
 	@Override
 	public E set(final int index, final E element) {
-		final E returnValue = this.delegate.get(index);
+		final var returnValue = this.delegate.get(index);
 		this.delegate.set(index, element);
 		this.fireContentsChanged(this, index, index);
 		return returnValue;
diff --git a/src/main/java/sevenUnitsGUI/ExpressionConversionView.java b/src/main/java/sevenUnitsGUI/ExpressionConversionView.java
index 882c995..ce69365 100644
--- a/src/main/java/sevenUnitsGUI/ExpressionConversionView.java
+++ b/src/main/java/sevenUnitsGUI/ExpressionConversionView.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2021 Adrien Hopkins
+ * Copyright (C) 2021, 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -18,32 +18,32 @@ package sevenUnitsGUI;
 
 /**
  * A View that can convert unit expressions
- * 
+ *
  * @author Adrien Hopkins
- * @since v0.4.0
  * @since 2021-12-15
+ * @since v0.4.0
  */
 public interface ExpressionConversionView extends View {
 	/**
 	 * @return unit expression to convert <em>from</em>
-	 * @since v0.4.0
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	String getFromExpression();
 
 	/**
 	 * @return unit expression to convert <em>to</em>
-	 * @since v0.4.0
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	String getToExpression();
 
 	/**
 	 * Shows the output of an expression conversion to the user.
-	 * 
+	 *
 	 * @param uc unit conversion to show
-	 * @since v0.4.0
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	void showExpressionConversionOutput(UnitConversionRecord uc);
 }
diff --git a/src/main/java/sevenUnitsGUI/FilterComparator.java b/src/main/java/sevenUnitsGUI/FilterComparator.java
index 484a98f..ff942fb 100644
--- a/src/main/java/sevenUnitsGUI/FilterComparator.java
+++ b/src/main/java/sevenUnitsGUI/FilterComparator.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2018 Adrien Hopkins
+ * Copyright (C) 2018, 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -21,9 +21,9 @@ import java.util.Objects;
 
 /**
  * A comparator that compares strings using a filter.
- * 
+ *
  * @param <T> type of element being compared
- * 
+ *
  * @author Adrien Hopkins
  * @since 2019-01-15
  * @since v0.1.0
@@ -31,21 +31,21 @@ import java.util.Objects;
 final class FilterComparator<T> implements Comparator<T> {
 	/**
 	 * The filter that the comparator is filtered by.
-	 * 
+	 *
 	 * @since 2019-01-15
 	 * @since v0.1.0
 	 */
 	private final String filter;
 	/**
 	 * The comparator to use if the arguments are otherwise equal.
-	 * 
+	 *
 	 * @since 2019-01-15
 	 * @since v0.1.0
 	 */
 	private final Comparator<T> comparator;
 	/**
 	 * Whether or not the comparison is case-sensitive.
-	 * 
+	 *
 	 * @since 2019-04-14
 	 * @since v0.2.0
 	 */
@@ -53,7 +53,7 @@ final class FilterComparator<T> implements Comparator<T> {
 
 	/**
 	 * Creates the {@code FilterComparator}.
-	 * 
+	 *
 	 * @param filter
 	 * @since 2019-01-15
 	 * @since v0.1.0
@@ -64,7 +64,7 @@ final class FilterComparator<T> implements Comparator<T> {
 
 	/**
 	 * Creates the {@code FilterComparator}.
-	 * 
+	 *
 	 * @param filter     string to filter by
 	 * @param comparator comparator to fall back to if all else fails, null is
 	 *                   compareTo.
@@ -79,7 +79,7 @@ final class FilterComparator<T> implements Comparator<T> {
 
 	/**
 	 * Creates the {@code FilterComparator}.
-	 * 
+	 *
 	 * @param filter        string to filter by
 	 * @param comparator    comparator to fall back to if all else fails, null is
 	 *                      compareTo.
@@ -118,19 +118,18 @@ final class FilterComparator<T> implements Comparator<T> {
 		// elements that start with the filter always go first
 		if (str0.startsWith(this.filter) && !str1.startsWith(this.filter))
 			return -1;
-		else if (!str0.startsWith(this.filter) && str1.startsWith(this.filter))
+		if (!str0.startsWith(this.filter) && str1.startsWith(this.filter))
 			return 1;
 
 		// elements that contain the filter but don't start with them go next
 		if (str0.contains(this.filter) && !str1.contains(this.filter))
 			return -1;
-		else if (!str0.contains(this.filter) && !str1.contains(this.filter))
+		if (!str0.contains(this.filter) && !str1.contains(this.filter))
 			return 1;
 
 		// other elements go last
 		if (this.comparator == null)
 			return str0.compareTo(str1);
-		else
-			return this.comparator.compare(arg0, arg1);
+		return this.comparator.compare(arg0, arg1);
 	}
 }
diff --git a/src/main/java/sevenUnitsGUI/GridBagBuilder.java b/src/main/java/sevenUnitsGUI/GridBagBuilder.java
index fdbaee7..a9fede3 100644
--- a/src/main/java/sevenUnitsGUI/GridBagBuilder.java
+++ b/src/main/java/sevenUnitsGUI/GridBagBuilder.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2018 Adrien Hopkins
+ * Copyright (C) 2018, 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -21,7 +21,7 @@ import java.awt.Insets;
 
 /**
  * A builder for Java's {@link java.awt.GridBagConstraints} class.
- * 
+ *
  * @author Adrien Hopkins
  * @since 2018-11-30
  * @since v0.1.0
@@ -40,7 +40,7 @@ final class GridBagBuilder {
 	 * <p>
 	 * The default value is <code>RELATIVE</code>. <code>gridx</code> should be a
 	 * non-negative value.
-	 * 
+	 *
 	 * @serial
 	 * @see #clone()
 	 * @see java.awt.GridBagConstraints#gridy
@@ -58,7 +58,7 @@ final class GridBagBuilder {
 	 * <p>
 	 * The default value is <code>RELATIVE</code>. <code>gridy</code> should be a
 	 * non-negative value.
-	 * 
+	 *
 	 * @serial
 	 * @see #clone()
 	 * @see java.awt.GridBagConstraints#gridx
@@ -76,7 +76,7 @@ final class GridBagBuilder {
 	 * from <code>gridx</code> to the next to the last one in its row.
 	 * <p>
 	 * <code>gridwidth</code> should be non-negative and the default value is 1.
-	 * 
+	 *
 	 * @serial
 	 * @see #clone()
 	 * @see java.awt.GridBagConstraints#gridheight
@@ -96,7 +96,7 @@ final class GridBagBuilder {
 	 * <p>
 	 * <code>gridheight</code> should be a non-negative value and the default
 	 * value is 1.
-	 * 
+	 *
 	 * @serial
 	 * @see #clone()
 	 * @see java.awt.GridBagConstraints#gridwidth
@@ -119,7 +119,7 @@ final class GridBagBuilder {
 	 * <p>
 	 * The default value of this field is <code>0</code>. <code>weightx</code>
 	 * should be a non-negative value.
-	 * 
+	 *
 	 * @serial
 	 * @see #clone()
 	 * @see java.awt.GridBagConstraints#weighty
@@ -142,7 +142,7 @@ final class GridBagBuilder {
 	 * <p>
 	 * The default value of this field is <code>0</code>. <code>weighty</code>
 	 * should be a non-negative value.
-	 * 
+	 *
 	 * @serial
 	 * @see #clone()
 	 * @see java.awt.GridBagConstraints#weightx
@@ -173,7 +173,7 @@ final class GridBagBuilder {
 	 * <code>BELOW_BASELINE</code>, <code>BELOW_BASELINE_LEADING</code>, and
 	 * <code>BELOW_BASELINE_TRAILING</code>. The default value is
 	 * <code>CENTER</code>.
-	 * 
+	 *
 	 * @serial
 	 * @see #clone()
 	 * @see java.awt.ComponentOrientation
@@ -199,7 +199,7 @@ final class GridBagBuilder {
 	 * </ul>
 	 * <p>
 	 * The default value is <code>NONE</code>.
-	 * 
+	 *
 	 * @serial
 	 * @see #clone()
 	 */
@@ -212,7 +212,7 @@ final class GridBagBuilder {
 	 * amount of space between the component and the edges of its display area.
 	 * <p>
 	 * The default value is <code>new Insets(0, 0, 0, 0)</code>.
-	 * 
+	 *
 	 * @serial
 	 * @see #clone()
 	 */
@@ -226,7 +226,7 @@ final class GridBagBuilder {
 	 * is at least its minimum width plus <code>ipadx</code> pixels.
 	 * <p>
 	 * The default value is <code>0</code>.
-	 * 
+	 *
 	 * @serial
 	 * @see #clone()
 	 * @see java.awt.GridBagConstraints#ipady
@@ -241,7 +241,7 @@ final class GridBagBuilder {
 	 * least its minimum height plus <code>ipady</code> pixels.
 	 * <p>
 	 * The default value is 0.
-	 * 
+	 *
 	 * @serial
 	 * @see #clone()
 	 * @see java.awt.GridBagConstraints#ipadx
@@ -292,7 +292,6 @@ final class GridBagBuilder {
 			final int gridheight, final double weightx, final double weighty,
 			final int anchor, final int fill, final Insets insets, final int ipadx,
 			final int ipady) {
-		super();
 		this.gridx = gridx;
 		this.gridy = gridy;
 		this.gridwidth = gridwidth;
@@ -418,6 +417,7 @@ final class GridBagBuilder {
 
 	/**
 	 * @param anchor anchor to set
+	 * @return this, so that you can chain methods
 	 * @since 2018-11-30
 	 * @since v0.1.0
 	 */
@@ -428,6 +428,7 @@ final class GridBagBuilder {
 
 	/**
 	 * @param fill fill to set
+	 * @return this, so that you can chain methods
 	 * @since 2018-11-30
 	 * @since v0.1.0
 	 */
@@ -438,6 +439,7 @@ final class GridBagBuilder {
 
 	/**
 	 * @param insets insets to set
+	 * @return this, so that you can chain methods
 	 * @since 2018-11-30
 	 * @since v0.1.0
 	 */
@@ -448,6 +450,7 @@ final class GridBagBuilder {
 
 	/**
 	 * @param ipadx ipadx to set
+	 * @return this, so that you can chain methods
 	 * @since 2018-11-30
 	 * @since v0.1.0
 	 */
@@ -458,6 +461,7 @@ final class GridBagBuilder {
 
 	/**
 	 * @param ipady ipady to set
+	 * @return this, so that you can chain methods
 	 * @since 2018-11-30
 	 * @since v0.1.0
 	 */
@@ -468,6 +472,7 @@ final class GridBagBuilder {
 
 	/**
 	 * @param weightx weightx to set
+	 * @return this, so that you can chain methods
 	 * @since 2018-11-30
 	 * @since v0.1.0
 	 */
@@ -478,6 +483,7 @@ final class GridBagBuilder {
 
 	/**
 	 * @param weighty weighty to set
+	 * @return this, so that you can chain methods
 	 * @since 2018-11-30
 	 * @since v0.1.0
 	 */
diff --git a/src/main/java/sevenUnitsGUI/Main.java b/src/main/java/sevenUnitsGUI/Main.java
index ff61b3b..3ff2fd9 100644
--- a/src/main/java/sevenUnitsGUI/Main.java
+++ b/src/main/java/sevenUnitsGUI/Main.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022 Adrien Hopkins
+ * Copyright (C) 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -19,8 +19,8 @@ package sevenUnitsGUI;
 /**
  * The main code for the 7Units GUI
  *
- * @since v0.4.0
  * @since 2022-04-19
+ * @since v0.4.0
  */
 public final class Main {
 
@@ -28,8 +28,8 @@ public final class Main {
 	 * The main method that starts 7Units
 	 *
 	 * @param args commandline arguments
-	 * @since v0.4.0
 	 * @since 2022-04-19
+	 * @since v0.4.0
 	 */
 	public static void main(String[] args) {
 		View.createTabbedView();
diff --git a/src/main/java/sevenUnitsGUI/PrefixSearchRule.java b/src/main/java/sevenUnitsGUI/PrefixSearchRule.java
index 69f09e6..73d12bc 100644
--- a/src/main/java/sevenUnitsGUI/PrefixSearchRule.java
+++ b/src/main/java/sevenUnitsGUI/PrefixSearchRule.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022 Adrien Hopkins
+ * Copyright (C) 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -34,8 +34,8 @@ import sevenUnits.unit.UnitPrefix;
  * A search rule that applies a certain set of prefixes to a unit. It always
  * includes the original unit in the output map.
  *
- * @since v0.4.0
  * @since 2022-07-06
+ * @since v0.4.0
  */
 public final class PrefixSearchRule implements
 		Function<Map.Entry<String, LinearUnit>, Map<String, LinearUnit>> {
@@ -70,10 +70,10 @@ public final class PrefixSearchRule implements
 	 *
 	 * @param prefixes prefixes to apply
 	 * @return prefix rule
-	 * @since v0.4.0
 	 * @since 2022-07-06
+	 * @since v0.4.0
 	 */
-	public static final PrefixSearchRule getCoherentOnlyRule(
+	public static PrefixSearchRule getCoherentOnlyRule(
 			Set<UnitPrefix> prefixes) {
 		return new PrefixSearchRule(prefixes,
 				u -> u.isCoherent() && !u.getName().equals("kilogram"));
@@ -84,30 +84,25 @@ public final class PrefixSearchRule implements
 	 *
 	 * @param prefixes prefixes to apply
 	 * @return prefix rule
-	 * @since v0.4.0
 	 * @since 2022-07-06
+	 * @since v0.4.0
 	 */
-	public static final PrefixSearchRule getUniversalRule(
-			Set<UnitPrefix> prefixes) {
+	public static PrefixSearchRule getUniversalRule(Set<UnitPrefix> prefixes) {
 		return new PrefixSearchRule(prefixes, u -> true);
 	}
 
-	/**
-	 * The set of prefixes that will be applied to the unit.
-	 */
+	/** The set of prefixes that will be applied to the unit. */
 	private final Set<UnitPrefix> prefixes;
 
-	/**
-	 * Determines which units are given prefixes.
-	 */
+	/** Determines which units are given prefixes. */
 	private final Predicate<LinearUnit> prefixableUnitRule;
 
 	/**
 	 * @param prefixes           prefixes to add to units
 	 * @param prefixableUnitRule function that determines which units get
 	 *                           prefixes
-	 * @since v0.4.0
 	 * @since 2022-07-06
+	 * @since v0.4.0
 	 */
 	public PrefixSearchRule(Set<UnitPrefix> prefixes,
 			Predicate<LinearUnit> prefixableUnitRule) {
@@ -118,8 +113,8 @@ public final class PrefixSearchRule implements
 	@Override
 	public Map<String, LinearUnit> apply(Entry<String, LinearUnit> t) {
 		final Map<String, LinearUnit> outputUnits = new HashMap<>();
-		final String originalName = t.getKey();
-		final LinearUnit originalUnit = t.getValue();
+		final var originalName = t.getKey();
+		final var originalUnit = t.getValue();
 		outputUnits.put(originalName, originalUnit);
 		if (this.prefixableUnitRule.test(originalUnit)) {
 			for (final UnitPrefix prefix : this.prefixes) {
@@ -136,15 +131,15 @@ public final class PrefixSearchRule implements
 			return true;
 		if (!(obj instanceof PrefixSearchRule))
 			return false;
-		final PrefixSearchRule other = (PrefixSearchRule) obj;
+		final var other = (PrefixSearchRule) obj;
 		return Objects.equals(this.prefixableUnitRule, other.prefixableUnitRule)
 				&& Objects.equals(this.prefixes, other.prefixes);
 	}
 
 	/**
 	 * @return rule that determines which units get prefixes
-	 * @since v0.4.0
 	 * @since 2022-07-09
+	 * @since v0.4.0
 	 */
 	public Predicate<LinearUnit> getPrefixableUnitRule() {
 		return this.prefixableUnitRule;
@@ -152,8 +147,8 @@ public final class PrefixSearchRule implements
 
 	/**
 	 * @return the prefixes that are applied by this rule
-	 * @since v0.4.0
 	 * @since 2022-07-06
+	 * @since v0.4.0
 	 */
 	public Set<UnitPrefix> getPrefixes() {
 		return this.prefixes;
diff --git a/src/main/java/sevenUnitsGUI/Presenter.java b/src/main/java/sevenUnitsGUI/Presenter.java
index eba8438..d258e1f 100644
--- a/src/main/java/sevenUnitsGUI/Presenter.java
+++ b/src/main/java/sevenUnitsGUI/Presenter.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2021-2022 Adrien Hopkins
+ * Copyright (C) 2021-2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -16,12 +16,12 @@
  */
 package sevenUnitsGUI;
 
-import java.io.BufferedWriter;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
@@ -40,12 +40,14 @@ import sevenUnits.unit.BaseUnit;
 import sevenUnits.unit.BritishImperial;
 import sevenUnits.unit.LinearUnit;
 import sevenUnits.unit.LinearUnitValue;
+import sevenUnits.unit.LoadingException;
 import sevenUnits.unit.Metric;
 import sevenUnits.unit.Unit;
 import sevenUnits.unit.UnitDatabase;
 import sevenUnits.unit.UnitPrefix;
 import sevenUnits.unit.UnitType;
 import sevenUnits.unit.UnitValue;
+import sevenUnits.utils.NameSymbol;
 import sevenUnits.utils.Nameable;
 import sevenUnits.utils.ObjectProduct;
 import sevenUnits.utils.UncertainDouble;
@@ -55,9 +57,10 @@ import sevenUnitsGUI.StandardDisplayRules.UncertaintyBased;
 
 /**
  * An object that handles interactions between the view and the backend code
- * 
+ *
  * @author Adrien Hopkins
  * @since 2021-12-15
+ * @since v0.4.0
  */
 public final class Presenter {
 	/**
@@ -72,33 +75,25 @@ public final class Presenter {
 	private static final String DEFAULT_DIMENSIONS_FILEPATH = "/dimensionfile.txt";
 	/** The default place where exceptions are stored. */
 	private static final String DEFAULT_EXCEPTIONS_FILEPATH = "/metric_exceptions.txt";
+	/** A Predicate that returns true iff the argument is a full base unit */
+	private static final Predicate<Unit> IS_FULL_BASE = unit -> unit instanceof LinearUnit
+			&& ((LinearUnit) unit).isBase();
+	/**
+	 * The default locale, used in two situations:
+	 * <ul>
+	 * <li>If no text is available in your locale, uses text from this locale.
+	 * <li>Users are initialized with this locale.
+	 * </ul>
+	 */
+	static final String DEFAULT_LOCALE = "en";
 
-	private static final Path userConfigDir() {
-		if (System.getProperty("os.name").startsWith("Windows")) {
-			final String envFolder = System.getenv("LOCALAPPDATA");
-			if (envFolder == null || "".equals(envFolder)) {
-				return Path.of(System.getenv("USERPROFILE"), "AppData", "Local");
-			} else {
-				return Path.of(envFolder);
-			}
-		} else {
-			final String envFolder = System.getenv("XDG_CONFIG_HOME");
-			if (envFolder == null || "".equals(envFolder)) {
-				return Path.of(System.getenv("HOME"), ".config");
-			} else {
-				return Path.of(envFolder);
-			}
-		}
-	}
-
-	/** Gets a Path from a pathname in the config file. */
-	private static Path pathFromConfig(String pathname) {
-		return CONFIG_FILE.getParent().resolve(pathname);
-	}
+	private static final List<String> LOCAL_LOCALES = List.of("en", "fr");
+	private static final Path USER_LOCALES_DIR = userConfigDir()
+			.resolve("SevenUnits").resolve("locales");
 
 	/**
 	 * Adds default units and dimensions to a database.
-	 * 
+	 *
 	 * @param database database to add to
 	 * @since 2019-04-14
 	 * @since v0.2.0
@@ -125,14 +120,32 @@ public final class Presenter {
 		database.addDimension("Temperature", Metric.Dimensions.TEMPERATURE);
 	}
 
+	private static String displayRuleToString(
+			Function<UncertainDouble, String> numberDisplayRule) {
+		if (numberDisplayRule instanceof FixedDecimals)
+			return String.format("FIXED_DECIMALS %d",
+					((FixedDecimals) numberDisplayRule).decimalPlaces());
+		if (numberDisplayRule instanceof FixedPrecision)
+			return String.format("FIXED_PRECISION %d",
+					((FixedPrecision) numberDisplayRule).significantFigures());
+		if (numberDisplayRule instanceof UncertaintyBased)
+			return "UNCERTAINTY_BASED";
+		return numberDisplayRule.toString();
+	}
+
 	/**
-	 * @return text in About file
-	 * @since 2022-02-19
+	 * Determines where to wrap {@code toWrap} with a max line length of
+	 * {@code maxLineLength}. If no good spot is found, returns -1.
+	 *
+	 * @since 2024-08-22
+	 * @since v1.0.0
 	 */
-	public static final String getAboutText() {
-		return Presenter.getLinesFromResource("/about.txt").stream()
-				.map(Presenter::withoutComments).collect(Collectors.joining("\n"))
-				.replaceAll("\\[VERSION\\]", ProgramInfo.VERSION.toString());
+	private static int findLineSplit(String toWrap, int maxLineLength) {
+		for (var i = maxLineLength - 1; i >= 0; i--) {
+			if (Character.isWhitespace(toWrap.charAt(i)))
+				return i;
+		}
+		return -1;
 	}
 
 	/**
@@ -142,12 +155,13 @@ public final class Presenter {
 	 * @param filename filename to get resource from
 	 * @return contents of file
 	 * @since 2021-03-27
+	 * @since v0.3.0
 	 */
-	private static final List<String> getLinesFromResource(String filename) {
+	private static List<String> getLinesFromResource(String filename) {
 		final List<String> lines = new ArrayList<>();
 
-		try (InputStream stream = inputStream(filename);
-				Scanner scanner = new Scanner(stream)) {
+		try (var stream = inputStream(filename);
+				var scanner = new Scanner(stream)) {
 			while (scanner.hasNextLine()) {
 				lines.add(scanner.nextLine());
 			}
@@ -165,16 +179,59 @@ public final class Presenter {
 	 * @param filepath file to use as resource
 	 * @return obtained Path
 	 * @since 2021-03-27
+	 * @since v0.3.0
 	 */
-	private static final InputStream inputStream(String filepath) {
+	private static InputStream inputStream(String filepath) {
 		return Presenter.class.getResourceAsStream(filepath);
 	}
 
 	/**
+	 * Convert a linear unit value to a string, where the number is rounded to
+	 * the nearest integer.
+	 *
+	 * @since 2024-08-16
+	 * @since v1.0.0
+	 */
+	private static String linearUnitValueIntToString(LinearUnitValue uv) {
+		return Long.toString(Math.round(uv.getValueExact())) + " " + uv.getUnit();
+	}
+
+	private static Map.Entry<String, String> parseSettingLine(String line) {
+		final var equalsIndex = line.indexOf('=');
+		if (equalsIndex == -1)
+			throw new IllegalStateException(
+					"Settings file is malformed at line: " + line);
+
+		final var param = line.substring(0, equalsIndex);
+		final var value = line.substring(equalsIndex + 1);
+
+		return Map.entry(param, value);
+	}
+
+	/** Gets a Path from a pathname in the config file. */
+	private static Path pathFromConfig(String pathname) {
+		return CONFIG_FILE.getParent().resolve(pathname);
+	}
+
+	// ====== SETTINGS ======
+
+	private static String searchRuleToString(
+			Function<Map.Entry<String, LinearUnit>, Map<String, LinearUnit>> searchRule) {
+		if (PrefixSearchRule.NO_PREFIXES.equals(searchRule))
+			return "NO_PREFIXES";
+		if (PrefixSearchRule.COMMON_PREFIXES.equals(searchRule))
+			return "COMMON_PREFIXES";
+		if (PrefixSearchRule.ALL_METRIC_PREFIXES.equals(searchRule))
+			return "ALL_METRIC_PREFIXES";
+		return searchRule.toString();
+	}
+
+	/**
 	 * @return true iff a and b have any elements in common
 	 * @since 2022-04-19
+	 * @since v0.4.0
 	 */
-	private static final boolean sharesAnyElements(Set<?> a, Set<?> b) {
+	private static boolean sharesAnyElements(Set<?> a, Set<?> b) {
 		for (final Object e : a) {
 			if (b.contains(e))
 				return true;
@@ -182,20 +239,55 @@ public final class Presenter {
 		return false;
 	}
 
+	private static Path userConfigDir() {
+		if (System.getProperty("os.name").startsWith("Windows")) {
+			final var envFolder = System.getenv("LOCALAPPDATA");
+			if (envFolder == null || "".equals(envFolder))
+				return Path.of(System.getenv("USERPROFILE"), "AppData", "Local");
+			return Path.of(envFolder);
+		}
+		final var envFolder = System.getenv("XDG_CONFIG_HOME");
+		if (envFolder == null || "".equals(envFolder))
+			return Path.of(System.getenv("HOME"), ".config");
+		return Path.of(envFolder);
+	}
+
 	/**
 	 * @return {@code line} with any comments removed.
 	 * @since 2021-03-13
+	 * @since v0.3.0
 	 */
-	private static final String withoutComments(String line) {
-		final int index = line.indexOf('#');
+	private static String withoutComments(String line) {
+		final var index = line.indexOf('#');
 		return index == -1 ? line : line.substring(0, index);
 	}
 
-	// ====== SETTINGS ======
-
 	/**
-	 * The view that this presenter communicates with
+	 * Wraps a string, ensuring no line is longer than {@code maxLineLength}.
+	 *
+	 * @since 2024-08-22
+	 * @since v1.0.0
 	 */
+	private static String wrapString(String toWrap, int maxLineLength) {
+		final var wrapped = new StringBuilder(toWrap.length());
+		var remaining = toWrap;
+		while (remaining.length() > maxLineLength) {
+			final var spot = findLineSplit(toWrap, maxLineLength);
+			if (spot == -1) {
+				wrapped.append(remaining.substring(0, maxLineLength));
+				wrapped.append("-\n");
+				remaining = remaining.substring(maxLineLength).stripLeading();
+			} else {
+				wrapped.append(remaining.substring(0, spot));
+				wrapped.append("\n");
+				remaining = remaining.substring(spot + 1).stripLeading();
+			}
+		}
+		wrapped.append(remaining);
+		return wrapped.toString();
+	}
+
+	/** The view that this presenter communicates with */
 	private final View view;
 
 	/**
@@ -238,6 +330,12 @@ public final class Presenter {
 	 */
 	private final Set<String> metricExceptions;
 
+	/** maps locale names (e.g. 'en') to key-text maps */
+	final Map<String, Map<String, String>> locales;
+
+	/** name of locale in locales to use */
+	String userLocale;
+
 	/**
 	 * If this is true, views that show units as a list will have metric units
 	 * removed from the From unit list and imperial/USC units removed from the To
@@ -252,65 +350,61 @@ public final class Presenter {
 	private boolean showDuplicates = false;
 
 	/**
+	 * The default unit, prefix, dimension and exception data will only be loaded
+	 * if this variable is true.
+	 */
+	private boolean useDefaultDatafiles = true;
+
+	/** Custom unit datafiles that will be loaded by {@link #reloadData} */
+	private final Set<Path> customUnitFiles = new HashSet<>();
+	/** Custom dimension datafiles that will be loaded by {@link #reloadData} */
+	private final Set<Path> customDimensionFiles = new HashSet<>();
+	/** Custom exception datafiles that will be loaded by {@link #reloadData} */
+	private final Set<Path> customExceptionFiles = new HashSet<>();
+
+	/**
 	 * Creates a Presenter
-	 * 
+	 *
 	 * @param view the view that this presenter communicates with
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	public Presenter(View view) {
 		this.view = view;
 		this.database = new UnitDatabase();
-		addDefaults(this.database);
+		this.metricExceptions = new HashSet<>();
 
-		// load units and prefixes
-		try (final InputStream units = inputStream(DEFAULT_UNITS_FILEPATH)) {
-			this.database.loadUnitsFromStream(units);
-		} catch (final IOException e) {
-			throw new AssertionError("Loading of unitsfile.txt failed.", e);
-		}
-
-		// load dimensions
-		try (final InputStream dimensions = inputStream(
-				DEFAULT_DIMENSIONS_FILEPATH)) {
-			this.database.loadDimensionsFromStream(dimensions);
-		} catch (final IOException e) {
-			throw new AssertionError("Loading of dimensionfile.txt failed.", e);
-		}
-
-		// load metric exceptions
-		try {
-			this.metricExceptions = new HashSet<>();
-			try (InputStream exceptions = inputStream(DEFAULT_EXCEPTIONS_FILEPATH);
-					Scanner scanner = new Scanner(exceptions)) {
-				while (scanner.hasNextLine()) {
-					final String line = Presenter
-							.withoutComments(scanner.nextLine());
-					if (!line.isBlank()) {
-						this.metricExceptions.add(line);
-					}
-				}
-			}
-		} catch (final IOException e) {
-			throw new AssertionError("Loading of metric_exceptions.txt failed.",
-					e);
-		}
+		this.locales = this.loadLocales();
+		this.userLocale = DEFAULT_LOCALE;
 
 		// set default settings temporarily
 		if (Files.exists(CONFIG_FILE)) {
 			this.loadSettings(CONFIG_FILE);
 		}
 
-		// a Predicate that returns true iff the argument is a full base unit
-		final Predicate<Unit> isFullBase = unit -> unit instanceof LinearUnit
-				&& ((LinearUnit) unit).isBase();
+		this.reloadData();
 
 		// print out unit counts
-		System.out.printf(
-				"Successfully loaded %d units with %d unit names (%d base units).%n",
-				this.database.unitMapPrefixless(false).size(),
-				this.database.unitMapPrefixless(true).size(),
-				this.database.unitMapPrefixless(false).values().stream()
-						.filter(isFullBase).count());
+		System.out.println(this.loadStatMsg());
+	}
+
+	private void addLocaleFile(Map<String, Map<String, String>> locales,
+			Path file) throws IOException {
+		final Map<String, String> locale = new HashMap<>();
+		final var fileName = file.getName(file.getNameCount() - 1).toString();
+		final var localeName = fileName.substring(0, fileName.length() - 4);
+		try (var lines = Files.lines(file)) {
+			lines.forEach(line -> this.addLocaleLine(locale, line));
+		}
+		locales.put(localeName, locale);
+	}
+
+	private void addLocaleLine(Map<String, String> locale, String line) {
+		final var parts = line.split("=", 2);
+		if (parts.length < 2)
+			return;
+
+		locale.put(parts[0], parts[1]);
 	}
 
 	/**
@@ -319,201 +413,387 @@ public final class Presenter {
 	 * @param e entry
 	 * @return stream of entries, ready for flat-mapping
 	 * @since 2022-07-06
+	 * @since v0.4.0
 	 */
-	private final Stream<Map.Entry<String, Unit>> applySearchRule(
+	private Stream<Map.Entry<String, Unit>> applySearchRule(
 			Map.Entry<String, Unit> e) {
-		final Unit u = e.getValue();
+		final var u = e.getValue();
 		if (u instanceof LinearUnit) {
-			final String name = e.getKey();
+			final var name = e.getKey();
 			final Map.Entry<String, LinearUnit> linearEntry = Map.entry(name,
 					(LinearUnit) u);
 			return this.searchRule.apply(linearEntry).entrySet().stream().map(
 					entry -> Map.entry(entry.getKey(), (Unit) entry.getValue()));
-		} else
-			return Stream.of(e);
+		}
+		return Stream.of(e);
 	}
 
 	/**
 	 * Converts from the view's input expression to its output expression.
 	 * Displays an error message if any of the required fields are invalid.
-	 * 
+	 *
 	 * @throws UnsupportedOperationException if the view does not support
 	 *                                       expression-based conversion (does
 	 *                                       not implement
 	 *                                       {@link ExpressionConversionView})
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	public void convertExpressions() {
-		if (this.view instanceof ExpressionConversionView) {
-			final ExpressionConversionView xcview = (ExpressionConversionView) this.view;
+		if (!(this.view instanceof ExpressionConversionView))
+			throw new UnsupportedOperationException(
+					"This function can only be called when the view is an ExpressionConversionView");
+		final var xcview = (ExpressionConversionView) this.view;
 
-			final String fromExpression = xcview.getFromExpression();
-			final String toExpression = xcview.getToExpression();
+		final var fromExpression = xcview.getFromExpression();
+		final var toExpression = xcview.getToExpression();
 
-			// expressions must not be empty
-			if (fromExpression.isEmpty()) {
-				this.view.showErrorMessage("Parse Error",
-						"Please enter a unit expression in the From: box.");
-				return;
-			}
-			if (toExpression.isEmpty()) {
-				this.view.showErrorMessage("Parse Error",
-						"Please enter a unit expression in the To: box.");
-				return;
-			}
+		// expressions must not be empty
+		if (fromExpression.isEmpty()) {
+			this.view.showErrorMessage("Parse Error",
+					"Please enter a unit expression in the From: box.");
+			return;
+		}
+		if (toExpression.isEmpty()) {
+			this.view.showErrorMessage("Parse Error",
+					"Please enter a unit expression in the To: box.");
+			return;
+		}
 
-			// evaluate expressions
-			final LinearUnitValue from;
-			final Unit to;
-			try {
-				from = this.database.evaluateUnitExpression(fromExpression);
-			} catch (final IllegalArgumentException | NoSuchElementException e) {
-				this.view.showErrorMessage("Parse Error",
-						"Could not recognize text in From entry: " + e.getMessage());
-				return;
-			}
+		final Optional<UnitConversionRecord> uc;
+		if (this.database.containsUnitSetName(toExpression)) {
+			uc = this.convertExpressionToNamedMultiUnit(fromExpression,
+					toExpression);
+		} else if (toExpression.contains(";")) {
+			final var toExpressions = toExpression.split(";");
+			uc = this.convertExpressionToMultiUnit(fromExpression, toExpressions);
+		} else {
+			uc = this.convertExpressionToExpression(fromExpression, toExpression);
+		}
+
+		uc.ifPresent(xcview::showExpressionConversionOutput);
+	}
+
+	/**
+	 * Converts a unit expression to another expression.
+	 *
+	 * If an error happened, it is shown to the view and Optional.empty() is
+	 * returned.
+	 *
+	 * @since 2024-08-15
+	 * @since v1.0.0
+	 */
+	private Optional<UnitConversionRecord> convertExpressionToExpression(
+			String fromExpression, String toExpression) {
+		// evaluate expressions
+		final LinearUnitValue from;
+		final Unit to;
+		try {
+			from = this.database.evaluateUnitExpression(fromExpression);
+		} catch (final IllegalArgumentException | NoSuchElementException e) {
+			this.view.showErrorMessage("Parse Error",
+					"Could not recognize text in From entry: " + e.getMessage());
+			return Optional.empty();
+		}
+		try {
+			to = this.database.getUnitFromExpression(toExpression);
+		} catch (final IllegalArgumentException | NoSuchElementException e) {
+			this.view.showErrorMessage("Parse Error",
+					"Could not recognize text in To entry: " + e.getMessage());
+			return Optional.empty();
+		}
+
+		// convert and show output
+		if (!from.getUnit().canConvertTo(to)) {
+			this.view.showErrorMessage("Conversion Error",
+					"Cannot convert between \"" + fromExpression + "\" and \""
+							+ toExpression + "\".");
+			return Optional.empty();
+		}
+		final UncertainDouble uncertainValue;
+
+		// uncertainty is meaningless for non-linear units, so we will have
+		// to erase uncertainty information for them
+		if (to instanceof LinearUnit) {
+			final var toLinear = (LinearUnit) to;
+			uncertainValue = from.convertTo(toLinear).getValue();
+		} else {
+			final var value = from.asUnitValue().convertTo(to).getValue();
+			uncertainValue = UncertainDouble.of(value, 0);
+		}
+
+		final var uc = UnitConversionRecord.valueOf(fromExpression, toExpression,
+				"", this.numberDisplayRule.apply(uncertainValue));
+		return Optional.of(uc);
+
+	}
+
+	/**
+	 * Convert an expression to a MultiUnit. If an error happened, it is shown to
+	 * the view and Optional.empty() is returned.
+	 *
+	 * @since 2024-08-15
+	 * @since v1.0.0
+	 */
+	private Optional<UnitConversionRecord> convertExpressionToMultiUnit(
+			String fromExpression, String[] toExpressions) {
+		final LinearUnitValue from;
+		try {
+			from = this.database.evaluateUnitExpression(fromExpression);
+		} catch (final IllegalArgumentException | NoSuchElementException e) {
+			this.view.showErrorMessage("Parse Error",
+					"Could not recognize text in From entry: " + e.getMessage());
+			return Optional.empty();
+		}
+
+		final List<LinearUnit> toUnits = new ArrayList<>(toExpressions.length);
+		for (final String toExpression : toExpressions) {
 			try {
-				to = this.database.getUnitFromExpression(toExpression);
+				final var toI = this.database
+						.getUnitFromExpression(toExpression.trim());
+				if (!(toI instanceof LinearUnit)) {
+					this.view.showErrorMessage("Unit Type Error",
+							"Units separated by ';' must be linear; " + toI
+									+ " is not.");
+					return Optional.empty();
+				}
+				toUnits.add((LinearUnit) toI);
 			} catch (final IllegalArgumentException | NoSuchElementException e) {
 				this.view.showErrorMessage("Parse Error",
 						"Could not recognize text in To entry: " + e.getMessage());
-				return;
+				return Optional.empty();
 			}
+		}
+
+		final List<LinearUnitValue> toValues;
+		try {
+			toValues = from.convertToMultiple(toUnits);
+		} catch (final IllegalArgumentException e) {
+			this.view.showErrorMessage("Unit Error",
+					"Invalid units separated by ';': " + e.getMessage());
+			return Optional.empty();
+		}
 
-			// convert and show output
-			if (from.getUnit().canConvertTo(to)) {
-				final UncertainDouble uncertainValue;
+		final var toExpression = this.linearUnitValueSumToString(toValues);
+		return Optional.of(
+				UnitConversionRecord.valueOf(fromExpression, toExpression, "", ""));
+	}
 
-				// uncertainty is meaningless for non-linear units, so we will have
-				// to erase uncertainty information for them
-				if (to instanceof LinearUnit) {
-					final var toLinear = (LinearUnit) to;
-					uncertainValue = from.convertTo(toLinear).getValue();
-				} else {
-					final double value = from.asUnitValue().convertTo(to).getValue();
-					uncertainValue = UncertainDouble.of(value, 0);
-				}
+	/**
+	 * Convert an expression to a MultiUnit with a name from the database. If an
+	 * error happened, it is shown to the view and Optional.empty() is returned.
+	 *
+	 * @since 2024-08-15
+	 * @since v1.0.0
+	 */
+	private Optional<UnitConversionRecord> convertExpressionToNamedMultiUnit(
+			String fromExpression, String toName) {
+		final LinearUnitValue from;
+		try {
+			from = this.database.evaluateUnitExpression(fromExpression);
+		} catch (final IllegalArgumentException | NoSuchElementException e) {
+			this.view.showErrorMessage("Parse Error",
+					"Could not recognize text in From entry: " + e.getMessage());
+			return Optional.empty();
+		}
 
-				final UnitConversionRecord uc = UnitConversionRecord.valueOf(
-						fromExpression, toExpression, "",
-						this.numberDisplayRule.apply(uncertainValue));
-				xcview.showExpressionConversionOutput(uc);
-			} else {
-				this.view.showErrorMessage("Conversion Error",
-						"Cannot convert between \"" + fromExpression + "\" and \""
-								+ toExpression + "\".");
-			}
+		final var toUnits = this.database.getUnitSet(toName);
+		final List<LinearUnitValue> toValues;
+		try {
+			toValues = from.convertToMultiple(toUnits);
+		} catch (final IllegalArgumentException e) {
+			this.view.showErrorMessage("Unit Error",
+					"Invalid units separated by ';': " + e.getMessage());
+			return Optional.empty();
+		}
 
-		} else
-			throw new UnsupportedOperationException(
-					"This function can only be called when the view is an ExpressionConversionView");
+		final var toExpression = this.linearUnitValueSumToString(toValues);
+		return Optional.of(
+				UnitConversionRecord.valueOf(fromExpression, toExpression, "", ""));
 	}
 
 	/**
 	 * Converts from the view's input unit to its output unit. Displays an error
 	 * message if any of the required fields are invalid.
-	 * 
+	 *
 	 * @throws UnsupportedOperationException if the view does not support
 	 *                                       unit-based conversion (does not
 	 *                                       implement
 	 *                                       {@link UnitConversionView})
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	public void convertUnits() {
-		if (this.view instanceof UnitConversionView) {
-			final UnitConversionView ucview = (UnitConversionView) this.view;
+		if (!(this.view instanceof UnitConversionView))
+			throw new UnsupportedOperationException(
+					"This function can only be called when the view is a UnitConversionView.");
+		final var ucview = (UnitConversionView) this.view;
+
+		final var fromUnitOptional = ucview.getFromSelection();
+		final var toUnitOptional = ucview.getToSelection();
+		final var inputValueString = ucview.getInputValue();
+
+		// extract values from optionals
+		final String fromUnitString, toUnitString;
+		if (!fromUnitOptional.isPresent()) {
+			this.view.showErrorMessage("Unit Selection Error",
+					"Please specify a From unit");
+			return;
+		}
+		fromUnitString = fromUnitOptional.orElseThrow();
+		if (!toUnitOptional.isPresent()) {
+			this.view.showErrorMessage("Unit Selection Error",
+					"Please specify a To unit");
+			return;
+		}
+		toUnitString = toUnitOptional.orElseThrow();
 
-			final Optional<String> fromUnitOptional = ucview.getFromSelection();
-			final Optional<String> toUnitOptional = ucview.getToSelection();
-			final String inputValueString = ucview.getInputValue();
+		// convert strings to data, checking if anything is invalid
+		final Unit fromUnit;
+		final UncertainDouble uncertainValue;
 
-			// extract values from optionals
-			final String fromUnitString, toUnitString;
-			if (fromUnitOptional.isPresent()) {
-				fromUnitString = fromUnitOptional.orElseThrow();
-			} else {
-				this.view.showErrorMessage("Unit Selection Error",
-						"Please specify a From unit");
-				return;
-			}
-			if (toUnitOptional.isPresent()) {
-				toUnitString = toUnitOptional.orElseThrow();
-			} else {
-				this.view.showErrorMessage("Unit Selection Error",
-						"Please specify a To unit");
-				return;
-			}
-
-			// convert strings to data, checking if anything is invalid
-			final Unit fromUnit, toUnit;
-			final UncertainDouble uncertainValue;
-
-			if (this.database.containsUnitName(fromUnitString)) {
-				fromUnit = this.database.getUnit(fromUnitString);
-			} else
-				throw this.viewError("Nonexistent From unit: %s", fromUnitString);
-			if (this.database.containsUnitName(toUnitString)) {
-				toUnit = this.database.getUnit(toUnitString);
-			} else
-				throw this.viewError("Nonexistent To unit: %s", toUnitString);
-			try {
-				uncertainValue = UncertainDouble
-						.fromRoundedString(inputValueString);
-			} catch (final NumberFormatException e) {
-				this.view.showErrorMessage("Value Error",
-						"Invalid value " + inputValueString);
-				return;
-			}
+		if (!this.database.containsUnitName(fromUnitString))
+			throw this.viewError("Nonexistent From unit: %s", fromUnitString);
+		fromUnit = this.database.getUnit(fromUnitString);
+		try {
+			uncertainValue = UncertainDouble.fromRoundedString(inputValueString);
+		} catch (final NumberFormatException e) {
+			this.view.showErrorMessage("Value Error",
+					"Invalid value " + inputValueString);
+			return;
+		}
+		if (this.database.containsUnitName(toUnitString)) {
+			final var toUnit = this.database.getUnit(toUnitString);
+			ucview.showUnitConversionOutput(
+					this.convertUnitToUnit(fromUnitString, toUnitString,
+							inputValueString, fromUnit, toUnit, uncertainValue));
+		} else if (this.database.containsUnitSetName(toUnitString)) {
+			final var toMulti = this.database.getUnitSet(toUnitString);
+			ucview.showUnitConversionOutput(this.convertUnitToMulti(fromUnitString,
+					inputValueString, fromUnit, toMulti, uncertainValue));
+		} else
+			throw this.viewError("Nonexistent To unit: %s", toUnitString);
+	}
 
+	private UnitConversionRecord convertUnitToMulti(String fromUnitString,
+			String inputValueString, Unit fromUnit, List<LinearUnit> toMulti,
+			UncertainDouble uncertainValue) {
+		for (final LinearUnit toUnit : toMulti) {
 			if (!fromUnit.canConvertTo(toUnit))
 				throw this.viewError("Could not convert between %s and %s",
 						fromUnit, toUnit);
+		}
 
-			// convert - we will need to erase uncertainty for non-linear units, so
-			// we need to treat linear and non-linear units differently
-			final String outputValueString;
-			if (fromUnit instanceof LinearUnit && toUnit instanceof LinearUnit) {
-				final LinearUnit fromLinear = (LinearUnit) fromUnit;
-				final LinearUnit toLinear = (LinearUnit) toUnit;
-				final LinearUnitValue initialValue = LinearUnitValue.of(fromLinear,
-						uncertainValue);
-				final LinearUnitValue converted = initialValue.convertTo(toLinear);
-
-				outputValueString = this.numberDisplayRule
-						.apply(converted.getValue());
-			} else {
-				final UnitValue initialValue = UnitValue.of(fromUnit,
-						uncertainValue.value());
-				final UnitValue converted = initialValue.convertTo(toUnit);
+		final LinearUnitValue initValue;
+		if (fromUnit instanceof LinearUnit) {
+			final var fromLinear = (LinearUnit) fromUnit;
+			initValue = LinearUnitValue.of(fromLinear, uncertainValue);
+		} else {
+			initValue = UnitValue.of(fromUnit, uncertainValue.value())
+					.convertToBase(NameSymbol.EMPTY);
+		}
 
-				outputValueString = this.numberDisplayRule
-						.apply(UncertainDouble.of(converted.getValue(), 0));
-			}
+		final var converted = initValue.convertToMultiple(toMulti);
+		final var toExpression = this.linearUnitValueSumToString(converted);
+		return UnitConversionRecord.valueOf(fromUnitString, toExpression,
+				inputValueString, "");
 
-			ucview.showUnitConversionOutput(
-					UnitConversionRecord.valueOf(fromUnitString, toUnitString,
-							inputValueString, outputValueString));
-		} else
-			throw new UnsupportedOperationException(
-					"This function can only be called when the view is a UnitConversionView.");
+	}
+
+	private UnitConversionRecord convertUnitToUnit(String fromUnitString,
+			String toUnitString, String inputValueString, Unit fromUnit,
+			Unit toUnit, UncertainDouble uncertainValue) {
+		if (!fromUnit.canConvertTo(toUnit))
+			throw this.viewError("Could not convert between %s and %s", fromUnit,
+					toUnit);
+
+		// convert - we will need to erase uncertainty for non-linear units, so
+		// we need to treat linear and non-linear units differently
+		final String outputValueString;
+		if (fromUnit instanceof LinearUnit && toUnit instanceof LinearUnit) {
+			final var fromLinear = (LinearUnit) fromUnit;
+			final var toLinear = (LinearUnit) toUnit;
+			final var initialValue = LinearUnitValue.of(fromLinear,
+					uncertainValue);
+			final var converted = initialValue.convertTo(toLinear);
+
+			outputValueString = this.numberDisplayRule.apply(converted.getValue());
+		} else {
+			final var initialValue = UnitValue.of(fromUnit,
+					uncertainValue.value());
+			final var converted = initialValue.convertTo(toUnit);
+
+			outputValueString = this.numberDisplayRule
+					.apply(UncertainDouble.of(converted.getValue(), 0));
+		}
+
+		return UnitConversionRecord.valueOf(fromUnitString, toUnitString,
+				inputValueString, outputValueString);
 	}
 
 	/**
 	 * @return true iff duplicate units are shown in unit lists
 	 * @since 2022-03-30
+	 * @since v0.4.0
 	 */
 	public boolean duplicatesShown() {
 		return this.showDuplicates;
 	}
 
+	private String formatAboutText(Stream<String> rawLines) {
+		return rawLines.map(Presenter::withoutComments)
+				.collect(Collectors.joining("\n"))
+				.replaceAll("\\[VERSION\\]", ProgramInfo.VERSION.toString())
+				.replaceAll("\\[LOADSTATS\\]", wrapString(this.loadStatMsg(), 72));
+	}
+
+	/**
+	 * @return text in About file
+	 * @since 2022-02-19
+	 * @since v0.4.0
+	 */
+	public String getAboutText() {
+		final var customFilepath = Presenter
+				.pathFromConfig("about/" + this.userLocale + ".txt");
+		if (Files.exists(customFilepath)) {
+			try (var lines = Files.lines(customFilepath)) {
+				return this.formatAboutText(lines);
+			} catch (final IOException e) {
+				final var filename = String.format("/about/%s.txt",
+						this.userLocale);
+				return this.formatAboutText(
+						Presenter.getLinesFromResource(filename).stream());
+			}
+		}
+		if (LOCAL_LOCALES.contains(this.userLocale)) {
+			final var filename = String.format("/about/%s.txt", this.userLocale);
+			return this.formatAboutText(
+					Presenter.getLinesFromResource(filename).stream());
+		}
+		final var filename = String.format("/about/%s.txt", DEFAULT_LOCALE);
+		return this
+				.formatAboutText(Presenter.getLinesFromResource(filename).stream());
+
+	}
+
+	/**
+	 * @return set of all locales available to select
+	 * @since 2025-02-21
+	 * @since v1.0.0
+	 */
+	public Set<String> getAvailableLocales() {
+		return this.locales.keySet();
+	}
+
 	/**
 	 * Gets a name for this dimension using the database
 	 *
 	 * @param dimension dimension to name
 	 * @return name of dimension
 	 * @since 2022-04-16
+	 * @since v0.4.0
 	 */
-	final String getDimensionName(ObjectProduct<BaseDimension> dimension) {
+	String getDimensionName(ObjectProduct<BaseDimension> dimension) {
 		// find this dimension in the database and get its name
 		// if it isn't there, use the dimension's toString instead
 		return this.database.dimensionMap().values().stream()
@@ -522,9 +802,24 @@ public final class Presenter {
 	}
 
 	/**
+	 * Gets the correct text for a provided ID. If this text is available in the
+	 * user's locale, that text is provided. Otherwise, text is taken from the
+	 * system default locale {@link #DEFAULT_LOCALE}.
+	 *
+	 * @param textID ID of text to get (used in locale files)
+	 * @return text to be displayed
+	 */
+	public String getLocalizedText(String textID) {
+		final var userLocale = this.locales.get(this.userLocale);
+		final var defaultLocale = this.locales.get(DEFAULT_LOCALE);
+		return userLocale.getOrDefault(textID, defaultLocale.get(textID));
+	}
+
+	/**
 	 * @return the rule that is used by this presenter to convert numbers into
 	 *         strings
 	 * @since 2022-04-10
+	 * @since v0.4.0
 	 */
 	public Function<UncertainDouble, String> getNumberDisplayRule() {
 		return this.numberDisplayRule;
@@ -534,6 +829,7 @@ public final class Presenter {
 	 * @return the rule that is used by this presenter to convert strings into
 	 *         numbers
 	 * @since 2022-04-10
+	 * @since v0.4.0
 	 */
 	@SuppressWarnings("unused") // not implemented yet
 	private Function<String, UncertainDouble> getNumberParsingRule() {
@@ -543,6 +839,7 @@ public final class Presenter {
 	/**
 	 * @return the rule that determines whether a set of prefixes is valid
 	 * @since 2022-04-19
+	 * @since v0.4.0
 	 */
 	public Predicate<List<UnitPrefix>> getPrefixRepetitionRule() {
 		return this.prefixRepetitionRule;
@@ -551,6 +848,7 @@ public final class Presenter {
 	/**
 	 * @return the rule that determines which units are prefixed
 	 * @since 2022-07-08
+	 * @since v0.4.0
 	 */
 	public Function<Map.Entry<String, LinearUnit>, Map<String, LinearUnit>> getSearchRule() {
 		return this.searchRule;
@@ -559,6 +857,7 @@ public final class Presenter {
 	/**
 	 * @return a search rule that shows all single prefixes
 	 * @since 2022-07-08
+	 * @since v0.4.0
 	 */
 	public Function<Map.Entry<String, LinearUnit>, Map<String, LinearUnit>> getUniversalSearchRule() {
 		return PrefixSearchRule.getCoherentOnlyRule(
@@ -566,19 +865,49 @@ public final class Presenter {
 	}
 
 	/**
+	 * @return user's selected locale
+	 * @since 2025-02-21
+	 * @since v1.0.0
+	 */
+	public String getUserLocale() {
+		return this.userLocale;
+	}
+
+	/**
 	 * @return the view associated with this presenter
 	 * @since 2022-04-19
+	 * @since v0.4.0
 	 */
 	public View getView() {
 		return this.view;
 	}
 
 	/**
+	 * Accepts a list of errors. If that list is non-empty, prints an error
+	 * message and alerts the user.
+	 *
+	 * @since 2024-08-22
+	 * @since v1.0.0
+	 */
+	private void handleLoadErrors(List<LoadingException> errors) {
+		if (!errors.isEmpty()) {
+			final var errorMessage = String.format(
+					"%d error(s) happened while loading file:\n%s\n", errors.size(),
+					errors.stream().map(Throwable::getMessage)
+							.collect(Collectors.joining("\n")));
+			System.err.print(errorMessage);
+			this.view.showErrorMessage(errors.size() + "Loading Error(s)",
+					errorMessage);
+		}
+	}
+
+	/**
 	 * @return whether or not the provided unit is semi-metric (i.e. an
 	 *         exception)
 	 * @since 2022-04-16
+	 * @since v0.4.0
 	 */
-	final boolean isSemiMetric(Unit u) {
+	boolean isSemiMetric(Unit u) {
 		// determine if u is an exception
 		final var primaryName = u.getPrimaryName();
 		final var symbol = u.getSymbol();
@@ -590,27 +919,127 @@ public final class Presenter {
 	}
 
 	/**
+	 * Convert a list of LinearUnitValues that you would get from a unit-set
+	 * conversion to a string. All but the last have their numbers rendered as
+	 * integers, since they are always integers. The last one follows the usual
+	 * number display rule.
+	 *
+	 * @since 2024-08-16
+	 * @since v1.0.0
+	 */
+	private String linearUnitValueSumToString(List<LinearUnitValue> values) {
+		final var integerPart = values.subList(0, values.size() - 1).stream()
+				.map(Presenter::linearUnitValueIntToString)
+				.collect(Collectors.joining(" + "));
+		final var last = values.get(values.size() - 1);
+		return integerPart + " + " + this.numberDisplayRule.apply(last.getValue())
+				+ " " + last.getUnit();
+	}
+
+	/** Load units, prefixes and dimensions from the default files. */
+	private void loadDefaultData() {
+		// load units and prefixes
+		try (final var units = inputStream(DEFAULT_UNITS_FILEPATH)) {
+			this.handleLoadErrors(this.database.loadUnitsFromStream(units));
+		} catch (final IOException e) {
+			throw new AssertionError("Loading of unitsfile.txt failed.", e);
+		}
+
+		// load dimensions
+		try (final var dimensions = inputStream(DEFAULT_DIMENSIONS_FILEPATH)) {
+			this.handleLoadErrors(
+					this.database.loadDimensionsFromStream(dimensions));
+		} catch (final IOException e) {
+			throw new AssertionError("Loading of dimensionfile.txt failed.", e);
+		}
+
+		// load metric exceptions
+		try {
+			try (var exceptions = inputStream(DEFAULT_EXCEPTIONS_FILEPATH);
+					var scanner = new Scanner(exceptions)) {
+				while (scanner.hasNextLine()) {
+					final var line = Presenter.withoutComments(scanner.nextLine());
+					if (!line.isBlank()) {
+						this.metricExceptions.add(line);
+					}
+				}
+			}
+		} catch (final IOException e) {
+			throw new AssertionError("Loading of metric_exceptions.txt failed.",
+					e);
+		}
+	}
+
+	private void loadExceptionFile(Path exceptionFile) {
+		try (var lines = Files.lines(exceptionFile)) {
+			lines.map(Presenter::withoutComments)
+					.forEach(this.metricExceptions::add);
+		} catch (final IOException e) {
+			this.view.showErrorMessage("File Load Error",
+					"Error loading configured metric exception file \""
+							+ exceptionFile + "\": " + e.getLocalizedMessage());
+		}
+	}
+
+	/**
+	 * Loads all available locales, including custom ones, into a map.
+	 *
+	 * @return map containing locales
+	 */
+	private Map<String, Map<String, String>> loadLocales() {
+		final Map<String, Map<String, String>> locales = new HashMap<>();
+		for (final String localeName : LOCAL_LOCALES) {
+			final Map<String, String> locale = new HashMap<>();
+			final var filename = "/locales/" + localeName + ".txt";
+			getLinesFromResource(filename)
+					.forEach(line -> this.addLocaleLine(locale, line));
+			locales.put(localeName, locale);
+		}
+
+		if (Files.exists(USER_LOCALES_DIR)) {
+			try (var files = Files.list(USER_LOCALES_DIR)) {
+				files.forEach(localeFile -> {
+					try {
+						this.addLocaleFile(locales, localeFile);
+					} catch (final IOException e) {
+						e.printStackTrace();
+					}
+				});
+			} catch (final IOException e) {
+				e.printStackTrace();
+			}
+		}
+		return locales;
+	}
+
+	/**
 	 * Loads settings from the user's settings file and applies them to the
 	 * presenter.
 	 *
 	 * @param settingsFile file settings should be loaded from
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	void loadSettings(Path settingsFile) {
-		for (Map.Entry<String, String> setting : settingsFromFile(settingsFile)) {
-			final String value = setting.getValue();
+		this.customDimensionFiles.clear();
+		this.customExceptionFiles.clear();
+		this.customUnitFiles.clear();
+
+		for (final Map.Entry<String, String> setting : this
+				.settingsFromFile(settingsFile)) {
+			final var value = setting.getValue();
 
 			switch (setting.getKey()) {
 			// set manually to avoid the unnecessary saving of the non-manual
 			// methods
 			case "custom_dimension_file":
-				this.database.loadDimensionFile(pathFromConfig(value));
+				this.customDimensionFiles.add(pathFromConfig(value));
 				break;
 			case "custom_exception_file":
-				this.loadExceptionFile(pathFromConfig(value));
+				this.customExceptionFiles.add(pathFromConfig(value));
 				break;
 			case "custom_unit_file":
-				this.database.loadUnitsFile(pathFromConfig(value));
+				this.customUnitFiles.add(pathFromConfig(value));
 				break;
 			case "number_display_rule":
 				this.setDisplayRuleFromString(value);
@@ -621,14 +1050,28 @@ public final class Presenter {
 				this.database.setPrefixRepetitionRule(this.prefixRepetitionRule);
 				break;
 			case "one_way":
-				this.oneWayConversionEnabled = Boolean.valueOf(value);
+				this.oneWayConversionEnabled = Boolean.parseBoolean(value);
 				break;
 			case "include_duplicates":
-				this.showDuplicates = Boolean.valueOf(value);
+				this.showDuplicates = Boolean.parseBoolean(value);
 				break;
 			case "search_prefix_rule":
 				this.setSearchRuleFromString(value);
 				break;
+			case "use_default_datafiles":
+				this.useDefaultDatafiles = Boolean.parseBoolean(value);
+				break;
+			case "locale":
+				if (this.locales.containsKey(value)) {
+					this.userLocale = value;
+				} else {
+					System.err.printf("Warning: unrecognized locale \"%s\".%n",
+							value);
+					this.view.showErrorMessage("Unrecognized Locale",
+							"Could not find locale \"" + value
+									+ "\", resetting to default.");
+				}
+				break;
 			default:
 				System.err.printf("Warning: unrecognized setting \"%s\".%n",
 						setting.getKey());
@@ -641,86 +1084,38 @@ public final class Presenter {
 		}
 	}
 
-	private List<Map.Entry<String, String>> settingsFromFile(Path settingsFile) {
-		try (Stream<String> lines = Files.lines(settingsFile)) {
-			return lines.map(Presenter::withoutComments)
-					.filter(line -> !line.isBlank()).map(Presenter::parseSettingLine)
-					.toList();
-		} catch (final IOException e) {
-			this.view.showErrorMessage("Settings Loading Error",
-					"Error loading settings file.  Using default settings.");
-			return null;
-		}
-	}
-
-	private static Map.Entry<String, String> parseSettingLine(String line) {
-		final int equalsIndex = line.indexOf('=');
-		if (equalsIndex == -1)
-			throw new IllegalStateException(
-					"Settings file is malformed at line: " + line);
-
-		final String param = line.substring(0, equalsIndex);
-		final String value = line.substring(equalsIndex + 1);
-
-		return Map.entry(param, value);
-	}
-
-	private void setSearchRuleFromString(String ruleString) {
-		switch (ruleString) {
-		case "NO_PREFIXES":
-			this.searchRule = PrefixSearchRule.NO_PREFIXES;
-			break;
-		case "COMMON_PREFIXES":
-			this.searchRule = PrefixSearchRule.COMMON_PREFIXES;
-			break;
-		case "ALL_METRIC_PREFIXES":
-			this.searchRule = PrefixSearchRule.ALL_METRIC_PREFIXES;
-			break;
-		default:
-			System.err.printf(
-					"Warning: unrecognized value for search_prefix_rule: %s\n",
-					ruleString);
-		}
-	}
-
-	private void setDisplayRuleFromString(String ruleString) {
-		String[] tokens = ruleString.split(" ");
-		switch (tokens[0]) {
-		case "FIXED_DECIMALS":
-			final int decimals = Integer.parseInt(tokens[1]);
-			this.numberDisplayRule = StandardDisplayRules.fixedDecimals(decimals);
-			break;
-		case "FIXED_PRECISION":
-			final int sigDigs = Integer.parseInt(tokens[1]);
-			this.numberDisplayRule = StandardDisplayRules.fixedPrecision(sigDigs);
-			break;
-		case "UNCERTAINTY_BASED":
-			this.numberDisplayRule = StandardDisplayRules.uncertaintyBased();
-			break;
-		default:
-			this.numberDisplayRule = StandardDisplayRules
-					.getStandardRule(ruleString);
-			break;
-		}
-	}
-
-	private void loadExceptionFile(Path exceptionFile) {
-		try (Stream<String> lines = Files.lines(exceptionFile)) {
-			lines.map(Presenter::withoutComments)
-					.forEach(this.metricExceptions::add);
-		} catch (IOException e) {
-			this.view.showErrorMessage("File Load Error",
-					"Error loading configured metric exception file \""
-							+ exceptionFile + "\": " + e.getLocalizedMessage());
-		}
+	/**
+	 * @return a message showing how much stuff has been loaded
+	 * @since 2024-08-22
+	 * @since v1.0.0
+	 */
+	private String loadStatMsg() {
+		return this.getLocalizedText("load_stat_msg")
+				.replace("[u]",
+						Integer.toString(
+								this.database.unitMapPrefixless(false).size()))
+				.replace("[un]",
+						Integer
+								.toString(this.database.unitMapPrefixless(true).size()))
+				.replace("[b]",
+						Long.toString(this.database.unitMapPrefixless(false).values()
+								.stream().filter(IS_FULL_BASE).count()))
+				.replace("[p]",
+						Integer.toString(this.database.prefixMap(false).size()))
+				.replace("[pn]",
+						Integer.toString(this.database.prefixMap(true).size()))
+				.replace("[s]", Integer.toString(this.database.unitSetMap().size()))
+				.replace("[d]",
+						Integer.toString(this.database.dimensionMap().size()));
 	}
 
 	/**
 	 * @return true iff the One-Way Conversion feature is available (views that
 	 *         show units as a list will have metric units removed from the From
 	 *         unit list and imperial/USC units removed from the To unit list)
-	 * 
+	 *
 	 * @since 2022-03-30
+	 * @since v0.4.0
 	 */
 	public boolean oneWayConversionEnabled() {
 		return this.oneWayConversionEnabled;
@@ -730,22 +1125,23 @@ public final class Presenter {
 	 * Completes creation of the presenter. This part of the initialization
 	 * depends on the view's functions, so it cannot be run if the components
 	 * they depend on are not created yet.
-	 * 
+	 *
 	 * @since 2022-02-26
+	 * @since v0.4.0
 	 */
 	public void postViewInitialize() {
 		// unit conversion specific stuff
 		if (this.view instanceof UnitConversionView) {
-			final UnitConversionView ucview = (UnitConversionView) this.view;
+			final var ucview = (UnitConversionView) this.view;
 			ucview.setDimensionNames(this.database.dimensionMap().keySet());
 		}
 
 		this.updateView();
+		this.view.updateText();
 	}
 
 	void prefixSelected() {
-		final Optional<String> selectedPrefixName = this.view
-				.getViewedPrefixName();
+		final var selectedPrefixName = this.view.getViewedPrefixName();
 		final Optional<UnitPrefix> selectedPrefix = selectedPrefixName
 				.map(name -> this.database.containsPrefixName(name)
 						? this.database.getPrefix(name)
@@ -755,19 +1151,37 @@ public final class Presenter {
 						String.valueOf(prefix.getMultiplier())));
 	}
 
+	/** Clears then reloads all unit, prefix, dimension and exception data. */
+	public void reloadData() {
+		this.database.clear();
+		this.metricExceptions.clear();
+		addDefaults(this.database);
+
+		if (this.useDefaultDatafiles) {
+			this.loadDefaultData();
+		}
+
+		this.customUnitFiles.forEach(
+				path -> this.handleLoadErrors(this.database.loadUnitsFile(path)));
+		this.customDimensionFiles.forEach(path -> this
+				.handleLoadErrors(this.database.loadDimensionFile(path)));
+		this.customExceptionFiles.forEach(this::loadExceptionFile);
+	}
+
 	/**
 	 * Saves the presenter's current settings to the config file, creating it if
 	 * it doesn't exist.
-	 * 
+	 *
 	 * @return false iff the presenter could not write to the file
 	 * @since 2022-04-19
+	 * @since v0.4.0
 	 */
 	public boolean saveSettings() {
-		final Path configDir = CONFIG_FILE.getParent();
+		final var configDir = CONFIG_FILE.getParent();
 		if (!Files.exists(configDir)) {
 			try {
 				Files.createDirectories(configDir);
-			} catch (IOException e) {
+			} catch (final IOException e) {
 				return false;
 			}
 		}
@@ -775,64 +1189,32 @@ public final class Presenter {
 		return this.writeSettings(CONFIG_FILE);
 	}
 
-	/**
-	 * Saves the presenter's settings to the user settings file.
-	 * 
-	 * @param settingsFile file settings should be saved to
-	 * @since 2021-12-15
-	 */
-	boolean writeSettings(Path settingsFile) {
-		try (BufferedWriter writer = Files.newBufferedWriter(settingsFile)) {
-			writer.write(String.format("number_display_rule=%s\n",
-					displayRuleToString(this.numberDisplayRule)));
-			writer.write(
-					String.format("prefix_rule=%s\n", this.prefixRepetitionRule));
-			writer.write(
-					String.format("one_way=%s\n", this.oneWayConversionEnabled));
-			writer.write(
-					String.format("include_duplicates=%s\n", this.showDuplicates));
-			writer.write(String.format("search_prefix_rule=%s\n",
-					searchRuleToString(this.searchRule)));
-			return true;
-		} catch (final IOException e) {
-			e.printStackTrace();
-			this.view.showErrorMessage("I/O Error",
-					"Error occurred while saving settings: "
-							+ e.getLocalizedMessage());
-			return false;
+	private void setDisplayRuleFromString(String ruleString) {
+		final var tokens = ruleString.split(" ");
+		switch (tokens[0]) {
+		case "FIXED_DECIMALS":
+			final var decimals = Integer.parseInt(tokens[1]);
+			this.numberDisplayRule = StandardDisplayRules.fixedDecimals(decimals);
+			break;
+		case "FIXED_PRECISION":
+			final var sigDigs = Integer.parseInt(tokens[1]);
+			this.numberDisplayRule = StandardDisplayRules.fixedPrecision(sigDigs);
+			break;
+		case "UNCERTAINTY_BASED":
+			this.numberDisplayRule = StandardDisplayRules.uncertaintyBased();
+			break;
+		default:
+			this.numberDisplayRule = StandardDisplayRules
+					.getStandardRule(ruleString);
+			break;
 		}
 	}
 
-	private static String searchRuleToString(
-			Function<Map.Entry<String, LinearUnit>, Map<String, LinearUnit>> searchRule) {
-		if (PrefixSearchRule.NO_PREFIXES.equals(searchRule)) {
-			return "NO_PREFIXES";
-		} else if (PrefixSearchRule.COMMON_PREFIXES.equals(searchRule)) {
-			return "COMMON_PREFIXES";
-		} else if (PrefixSearchRule.ALL_METRIC_PREFIXES.equals(searchRule)) {
-			return "ALL_METRIC_PREFIXES";
-		} else
-			return searchRule.toString();
-	}
-
-	private static String displayRuleToString(
-			Function<UncertainDouble, String> numberDisplayRule) {
-		if (numberDisplayRule instanceof FixedDecimals) {
-			return String.format("FIXED_DECIMALS %d",
-					((FixedDecimals) numberDisplayRule).decimalPlaces());
-		} else if (numberDisplayRule instanceof FixedPrecision) {
-			return String.format("FIXED_PRECISION %d",
-					((FixedPrecision) numberDisplayRule).significantFigures());
-		} else if (numberDisplayRule instanceof UncertaintyBased) {
-			return "UNCERTAINTY_BASED";
-		} else
-			return numberDisplayRule.toString();
-	}
-
 	/**
 	 * @param numberDisplayRule the new rule that will be used by this presenter
 	 *                          to convert numbers into strings
 	 * @since 2022-04-10
+	 * @since v0.4.0
 	 */
 	public void setNumberDisplayRule(
 			Function<UncertainDouble, String> numberDisplayRule) {
@@ -843,6 +1225,7 @@ public final class Presenter {
 	 * @param numberParsingRule the new rule that will be used by this presenter
 	 *                          to convert strings into numbers
 	 * @since 2022-04-10
+	 * @since v0.4.0
 	 */
 	@SuppressWarnings("unused") // not implemented yet
 	private void setNumberParsingRule(
@@ -854,7 +1237,8 @@ public final class Presenter {
 	 * @param oneWayConversionEnabled whether not one-way conversion should be
 	 *                                enabled
 	 * @since 2022-03-30
-	 * @see {@link #isOneWayConversionEnabled}
+	 * @since v0.4.0
+	 * @see #oneWayConversionEnabled
 	 */
 	public void setOneWayConversionEnabled(boolean oneWayConversionEnabled) {
 		this.oneWayConversionEnabled = oneWayConversionEnabled;
@@ -865,6 +1249,7 @@ public final class Presenter {
 	 * @param prefixRepetitionRule the rule that determines whether a set of
 	 *                             prefixes is valid
 	 * @since 2022-04-19
+	 * @since v0.4.0
 	 */
 	public void setPrefixRepetitionRule(
 			Predicate<List<UnitPrefix>> prefixRepetitionRule) {
@@ -878,30 +1263,86 @@ public final class Presenter {
 	 *                   unit (including the unit itself) that should be
 	 *                   searchable.
 	 * @since 2022-07-08
+	 * @since v0.4.0
 	 */
 	public void setSearchRule(
 			Function<Map.Entry<String, LinearUnit>, Map<String, LinearUnit>> searchRule) {
 		this.searchRule = searchRule;
 	}
 
+	private void setSearchRuleFromString(String ruleString) {
+		switch (ruleString) {
+		case "NO_PREFIXES":
+			this.searchRule = PrefixSearchRule.NO_PREFIXES;
+			break;
+		case "COMMON_PREFIXES":
+			this.searchRule = PrefixSearchRule.COMMON_PREFIXES;
+			break;
+		case "ALL_METRIC_PREFIXES":
+			this.searchRule = PrefixSearchRule.ALL_METRIC_PREFIXES;
+			break;
+		default:
+			System.err.printf(
+					"Warning: unrecognized value for search_prefix_rule: %s\n",
+					ruleString);
+		}
+	}
+
 	/**
 	 * @param showDuplicateUnits whether or not duplicate units should be shown
 	 * @since 2022-03-30
+	 * @since v0.4.0
 	 */
 	public void setShowDuplicates(boolean showDuplicateUnits) {
 		this.showDuplicates = showDuplicateUnits;
 		this.updateView();
 	}
 
+	private List<Map.Entry<String, String>> settingsFromFile(Path settingsFile) {
+		try (var lines = Files.lines(settingsFile)) {
+			return lines.map(Presenter::withoutComments)
+					.filter(line -> !line.isBlank()).map(Presenter::parseSettingLine)
+					.toList();
+		} catch (final IOException e) {
+			this.view.showErrorMessage("Settings Loading Error",
+					"Error loading settings file.  Using default settings.");
+			return null;
+		}
+	}
+
+	/**
+	 * Sets whether or not the default datafiles will be loaded. This method
+	 * automatically updates the view's units.
+	 *
+	 * @param useDefaultDatafiles whether or not default datafiles should be
+	 *                            loaded
+	 */
+	public void setUseDefaultDatafiles(boolean useDefaultDatafiles) {
+		this.useDefaultDatafiles = useDefaultDatafiles;
+		this.reloadData();
+		this.updateView();
+	}
+
+	/**
+	 * Sets the user's locale, updating the view.
+	 *
+	 * @param userLocale locale to use
+	 */
+	public void setUserLocale(String userLocale) {
+		this.userLocale = userLocale;
+		this.view.updateText();
+	}
+
 	/**
 	 * Shows a unit in the unit viewer
 	 *
 	 * @param u unit to show
 	 * @since 2022-04-16
+	 * @since v0.4.0
 	 */
-	private final void showUnit(Unit u) {
+	private void showUnit(Unit u) {
 		final var nameSymbol = u.getNameSymbol();
-		final boolean isBase = u instanceof BaseUnit
+		final var isBase = u instanceof BaseUnit
 				|| u instanceof LinearUnit && ((LinearUnit) u).isBase();
 		final var definition = isBase ? "(Base unit)" : u.toDefinitionString();
 		final var dimensionString = this.getDimensionName(u.getDimension());
@@ -912,12 +1353,13 @@ public final class Presenter {
 	/**
 	 * Runs whenever a unit name is selected in the unit viewer. Gets the
 	 * description of a unit and displays it.
-	 * 
+	 *
 	 * @since 2022-04-10
+	 * @since v0.4.0
 	 */
 	void unitNameSelected() {
 		// get selected unit, if it's there and valid
-		final Optional<String> selectedUnitName = this.view.getViewedUnitName();
+		final var selectedUnitName = this.view.getViewedUnitName();
 		final Optional<Unit> selectedUnit = selectedUnitName
 				.map(unitName -> this.database.containsUnitName(unitName)
 						? this.database.getUnit(unitName)
@@ -927,12 +1369,13 @@ public final class Presenter {
 
 	/**
 	 * Updates the view's From and To units, if it has some
-	 * 
+	 *
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	public void updateView() {
 		if (this.view instanceof UnitConversionView) {
-			final UnitConversionView ucview = (UnitConversionView) this.view;
+			final var ucview = (UnitConversionView) this.view;
 			final var selectedDimensionName = ucview.getSelectedDimensionName();
 
 			// load units & prefixes into viewers
@@ -946,6 +1389,7 @@ public final class Presenter {
 					.entrySet().stream();
 			var toUnits = this.database.unitMapPrefixless(this.showDuplicates)
 					.entrySet().stream();
+			var unitSets = this.database.unitSetMap().entrySet().stream();
 
 			// filter by dimension, if one is selected
 			if (selectedDimensionName.isPresent()) {
@@ -955,6 +1399,8 @@ public final class Presenter {
 						u -> viewDimension.equals(u.getValue().getDimension()));
 				toUnits = toUnits.filter(
 						u -> viewDimension.equals(u.getValue().getDimension()));
+				unitSets = unitSets.filter(us -> viewDimension
+						.equals(us.getValue().get(0).getDimension()));
 			}
 
 			// filter by unit type, if desired
@@ -963,25 +1409,70 @@ public final class Presenter {
 						this::isSemiMetric) != UnitType.METRIC);
 				toUnits = toUnits.filter(u -> UnitType.getType(u.getValue(),
 						this::isSemiMetric) != UnitType.NON_METRIC);
+				// unit sets are never considered metric
+				unitSets = unitSets
+						.filter(us -> this.metricExceptions.contains(us.getKey()));
 			}
 
 			// set unit names
 			ucview.setFromUnitNames(fromUnits.flatMap(this::applySearchRule)
 					.map(Map.Entry::getKey).collect(Collectors.toSet()));
-			ucview.setToUnitNames(toUnits.flatMap(this::applySearchRule)
-					.map(Map.Entry::getKey).collect(Collectors.toSet()));
+			final var toUnitNames = toUnits.flatMap(this::applySearchRule)
+					.map(Map.Entry::getKey);
+			final var unitSetNames = unitSets.map(Map.Entry::getKey);
+			final var toNames = Stream.concat(toUnitNames, unitSetNames)
+					.collect(Collectors.toSet());
+			ucview.setToUnitNames(toNames);
 		}
 	}
 
+	/** @return true iff the default datafiles are being used */
+	public boolean usingDefaultDatafiles() {
+		return this.useDefaultDatafiles;
+	}
+
 	/**
 	 * @param message message to add
 	 * @param args    string formatting arguments for message
 	 * @return AssertionError stating that an error has happened in the view's
 	 *         code
 	 * @since 2022-04-09
+	 * @since v0.4.0
 	 */
 	private AssertionError viewError(String message, Object... args) {
 		return new AssertionError("View Programming Error (from " + this.view
 				+ "): " + String.format(message, args));
 	}
+
+	/**
+	 * Saves the presenter's settings to the user settings file.
+	 *
+	 * @param settingsFile file settings should be saved to
+	 * @since 2021-12-15
+	 * @since v0.4.0
+	 */
+	boolean writeSettings(Path settingsFile) {
+		try (var writer = Files.newBufferedWriter(settingsFile)) {
+			writer.write(String.format("number_display_rule=%s\n",
+					displayRuleToString(this.numberDisplayRule)));
+			writer.write(
+					String.format("prefix_rule=%s\n", this.prefixRepetitionRule));
+			writer.write(
+					String.format("one_way=%s\n", this.oneWayConversionEnabled));
+			writer.write(
+					String.format("include_duplicates=%s\n", this.showDuplicates));
+			writer.write(String.format("search_prefix_rule=%s\n",
+					searchRuleToString(this.searchRule)));
+			writer.write(String.format("use_default_datafiles=%s\n",
+					this.useDefaultDatafiles));
+			writer.write(String.format("locale=%s\n", this.userLocale));
+			return true;
+		} catch (final IOException e) {
+			e.printStackTrace();
+			this.view.showErrorMessage("I/O Error",
+					"Error occurred while saving settings: "
+							+ e.getLocalizedMessage());
+			return false;
+		}
+	}
 }
diff --git a/src/main/java/sevenUnitsGUI/SearchBoxList.java b/src/main/java/sevenUnitsGUI/SearchBoxList.java
index 8fba459..96f71de 100644
--- a/src/main/java/sevenUnitsGUI/SearchBoxList.java
+++ b/src/main/java/sevenUnitsGUI/SearchBoxList.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2019 Adrien Hopkins
+ * Copyright (C) 2019, 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -49,7 +49,7 @@ final class SearchBoxList<E> extends JPanel {
 
 	/**
 	 * The text to place in an empty search box.
-	 * 
+	 *
 	 * @since 2019-04-13
 	 * @since v0.2.0
 	 */
@@ -57,7 +57,7 @@ final class SearchBoxList<E> extends JPanel {
 
 	/**
 	 * The color to use for an empty foreground.
-	 * 
+	 *
 	 * @since 2019-04-13
 	 * @since v0.2.0
 	 */
@@ -82,8 +82,9 @@ final class SearchBoxList<E> extends JPanel {
 
 	/**
 	 * Creates an empty SearchBoxList
-	 * 
+	 *
 	 * @since 2022-02-19
+	 * @since v0.4.0
 	 */
 	public SearchBoxList() {
 		this(List.of(), null, false);
@@ -91,9 +92,10 @@ final class SearchBoxList<E> extends JPanel {
 
 	/**
 	 * Creates the {@code SearchBoxList}.
-	 * 
+	 *
 	 * @param itemsToFilter items to put in the list
 	 * @since 2019-04-14
+	 * @since v0.2.0
 	 */
 	public SearchBoxList(final Collection<E> itemsToFilter) {
 		this(itemsToFilter, null, false);
@@ -101,12 +103,12 @@ final class SearchBoxList<E> extends JPanel {
 
 	/**
 	 * Creates the {@code SearchBoxList}.
-	 * 
+	 *
 	 * @param itemsToFilter   items to put in the list
 	 * @param defaultOrdering default ordering of items after filtration
 	 *                        (null=Comparable)
 	 * @param caseSensitive   whether or not the filtration is case-sensitive
-	 * 
+	 *
 	 * @since 2019-04-13
 	 * @since v0.2.0
 	 */
@@ -147,7 +149,7 @@ final class SearchBoxList<E> extends JPanel {
 
 	/**
 	 * Adds an additional filter for searching.
-	 * 
+	 *
 	 * @param filter filter to add.
 	 * @since 2019-04-13
 	 * @since v0.2.0
@@ -158,7 +160,7 @@ final class SearchBoxList<E> extends JPanel {
 
 	/**
 	 * Resets the search filter.
-	 * 
+	 *
 	 * @since 2019-04-13
 	 * @since v0.2.0
 	 */
@@ -170,6 +172,7 @@ final class SearchBoxList<E> extends JPanel {
 	 * @return items available in search list, including items that are hidden by
 	 *         the search filter
 	 * @since 2022-03-30
+	 * @since v0.4.0
 	 */
 	public Collection<E> getItems() {
 		return Collections.unmodifiableCollection(this.itemsToFilter);
@@ -180,7 +183,7 @@ final class SearchBoxList<E> extends JPanel {
 	 * @since 2019-04-14
 	 * @since v0.2.0
 	 */
-	public final JTextField getSearchBox() {
+	public JTextField getSearchBox() {
 		return this.searchBox;
 	}
 
@@ -194,9 +197,8 @@ final class SearchBoxList<E> extends JPanel {
 	private Predicate<E> getSearchFilter(final String searchText) {
 		if (this.caseSensitive)
 			return item -> item.toString().contains(searchText);
-		else
-			return item -> item.toString().toLowerCase()
-					.contains(searchText.toLowerCase());
+		return item -> item.toString().toLowerCase()
+				.contains(searchText.toLowerCase());
 	}
 
 	/**
@@ -204,7 +206,7 @@ final class SearchBoxList<E> extends JPanel {
 	 * @since 2019-04-14
 	 * @since v0.2.0
 	 */
-	public final JList<E> getSearchList() {
+	public JList<E> getSearchList() {
 		return this.searchItems;
 	}
 
@@ -228,16 +230,16 @@ final class SearchBoxList<E> extends JPanel {
 
 	/**
 	 * Re-applies the filters.
-	 * 
+	 *
 	 * @since 2019-04-13
 	 * @since v0.2.0
 	 */
 	public void reapplyFilter() {
-		final String searchText = this.searchBoxEmpty ? ""
+		final var searchText = this.searchBoxEmpty ? ""
 				: this.searchBox.getText();
-		final FilterComparator<E> comparator = new FilterComparator<>(searchText,
+		final var comparator = new FilterComparator<>(searchText,
 				this.defaultOrdering, this.caseSensitive);
-		final Predicate<E> searchFilter = this.getSearchFilter(searchText);
+		final var searchFilter = this.getSearchFilter(searchText);
 
 		this.listModel.clear();
 		this.itemsToFilter.forEach(item -> {
@@ -255,7 +257,7 @@ final class SearchBoxList<E> extends JPanel {
 
 	/**
 	 * Runs whenever the search box gains focus.
-	 * 
+	 *
 	 * @param e focus event
 	 * @since 2019-04-13
 	 * @since v0.2.0
@@ -270,7 +272,7 @@ final class SearchBoxList<E> extends JPanel {
 
 	/**
 	 * Runs whenever the search box loses focus.
-	 * 
+	 *
 	 * @param e focus event
 	 * @since 2019-04-13
 	 * @since v0.2.0
@@ -288,7 +290,7 @@ final class SearchBoxList<E> extends JPanel {
 	 * <p>
 	 * Reapplies the search filter, and custom filters.
 	 * </p>
-	 * 
+	 *
 	 * @since 2019-04-14
 	 * @since v0.2.0
 	 */
@@ -296,11 +298,11 @@ final class SearchBoxList<E> extends JPanel {
 		if (this.searchBoxFocused) {
 			this.searchBoxEmpty = this.searchBox.getText().equals("");
 		}
-		final String searchText = this.searchBoxEmpty ? ""
+		final var searchText = this.searchBoxEmpty ? ""
 				: this.searchBox.getText();
-		final FilterComparator<E> comparator = new FilterComparator<>(searchText,
+		final var comparator = new FilterComparator<>(searchText,
 				this.defaultOrdering, this.caseSensitive);
-		final Predicate<E> searchFilter = this.getSearchFilter(searchText);
+		final var searchFilter = this.getSearchFilter(searchText);
 
 		// initialize list with items that match the filter then sort
 		this.listModel.clear();
@@ -323,6 +325,7 @@ final class SearchBoxList<E> extends JPanel {
 	 *
 	 * @param newItems new items to put in list
 	 * @since 2021-05-22
+	 * @since v0.3.0
 	 */
 	public void setItems(Collection<? extends E> newItems) {
 		this.itemsToFilter.clear();
@@ -332,8 +335,9 @@ final class SearchBoxList<E> extends JPanel {
 
 	/**
 	 * Manually updates the search box's item list.
-	 * 
+	 *
 	 * @since 2020-08-27
+	 * @since v0.3.0
 	 */
 	public void updateList() {
 		this.searchBoxTextChanged();
diff --git a/src/main/java/sevenUnitsGUI/StandardDisplayRules.java b/src/main/java/sevenUnitsGUI/StandardDisplayRules.java
index d00263b..16d31ae 100644
--- a/src/main/java/sevenUnitsGUI/StandardDisplayRules.java
+++ b/src/main/java/sevenUnitsGUI/StandardDisplayRules.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022 Adrien Hopkins
+ * Copyright (C) 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -28,28 +28,28 @@ import sevenUnits.utils.UncertainDouble;
  * A static utility class that can be used to make display rules for the
  * presenter.
  *
- * @since v0.4.0
  * @since 2022-04-18
+ * @since v0.4.0
  */
 public final class StandardDisplayRules {
 	/**
 	 * A rule that rounds to a fixed number of decimal places.
 	 *
-	 * @since v0.4.0
 	 * @since 2022-04-18
+	 * @since v0.4.0
 	 */
 	public static final class FixedDecimals
 			implements Function<UncertainDouble, String> {
+		/** Regular expression used for converting this to a string. */
 		public static final Pattern TO_STRING_PATTERN = Pattern
 				.compile("Round to (\\d+) decimal places");
-		/**
-		 * The number of places to round to.
-		 */
+		/** The number of places to round to. */
 		private final int decimalPlaces;
 
 		/**
 		 * @param decimalPlaces
 		 * @since 2022-04-18
+		 * @since v0.4.0
 		 */
 		private FixedDecimals(int decimalPlaces) {
 			this.decimalPlaces = decimalPlaces;
@@ -65,6 +65,7 @@ public final class StandardDisplayRules {
 		/**
 		 * @return the number of decimal places this rule rounds to
 		 * @since 2022-04-18
+		 * @since v0.4.0
 		 */
 		public int decimalPlaces() {
 			return this.decimalPlaces;
@@ -76,7 +77,7 @@ public final class StandardDisplayRules {
 				return true;
 			if (!(obj instanceof FixedDecimals))
 				return false;
-			final FixedDecimals other = (FixedDecimals) obj;
+			final var other = (FixedDecimals) obj;
 			if (this.decimalPlaces != other.decimalPlaces)
 				return false;
 			return true;
@@ -96,22 +97,22 @@ public final class StandardDisplayRules {
 	/**
 	 * A rule that rounds to a fixed number of significant digits.
 	 *
-	 * @since v0.4.0
 	 * @since 2022-04-18
+	 * @since v0.4.0
 	 */
 	public static final class FixedPrecision
 			implements Function<UncertainDouble, String> {
+		/** Regular expression used for converting this to a string. */
 		public static final Pattern TO_STRING_PATTERN = Pattern
 				.compile("Round to (\\d+) significant figures");
 
-		/**
-		 * The number of significant figures to round to.
-		 */
+		/** The number of significant figures to round to. */
 		private final MathContext mathContext;
 
 		/**
 		 * @param significantFigures
 		 * @since 2022-04-18
+		 * @since v0.4.0
 		 */
 		private FixedPrecision(int significantFigures) {
 			this.mathContext = new MathContext(significantFigures,
@@ -130,7 +131,7 @@ public final class StandardDisplayRules {
 				return true;
 			if (!(obj instanceof FixedPrecision))
 				return false;
-			final FixedPrecision other = (FixedPrecision) obj;
+			final var other = (FixedPrecision) obj;
 			if (this.mathContext == null) {
 				if (other.mathContext != null)
 					return false;
@@ -148,6 +149,7 @@ public final class StandardDisplayRules {
 		/**
 		 * @return the number of significant figures this rule rounds to
 		 * @since 2022-04-18
+		 * @since v0.4.0
 		 */
 		public int significantFigures() {
 			return this.mathContext.getPrecision();
@@ -165,8 +167,8 @@ public final class StandardDisplayRules {
 	 * This means the output will have around as many significant figures as the
 	 * input.
 	 *
-	 * @since v0.4.0
 	 * @since 2022-04-18
+	 * @since v0.4.0
 	 */
 	public static final class UncertaintyBased
 			implements Function<UncertainDouble, String> {
@@ -193,10 +195,10 @@ public final class StandardDisplayRules {
 	/**
 	 * @param decimalPlaces decimal places to round to
 	 * @return a rounding rule that rounds to fixed number of decimal places
-	 * @since v0.4.0
 	 * @since 2022-04-18
+	 * @since v0.4.0
 	 */
-	public static final FixedDecimals fixedDecimals(int decimalPlaces) {
+	public static FixedDecimals fixedDecimals(int decimalPlaces) {
 		return new FixedDecimals(decimalPlaces);
 	}
 
@@ -204,10 +206,10 @@ public final class StandardDisplayRules {
 	 * @param significantFigures significant figures to round to
 	 * @return a rounding rule that rounds to a fixed number of significant
 	 *         figures
-	 * @since v0.4.0
 	 * @since 2022-04-18
+	 * @since v0.4.0
 	 */
-	public static final FixedPrecision fixedPrecision(int significantFigures) {
+	public static FixedPrecision fixedPrecision(int significantFigures) {
 		return new FixedPrecision(significantFigures);
 	}
 
@@ -218,10 +220,10 @@ public final class StandardDisplayRules {
 	 * @return display rule
 	 * @throws IllegalArgumentException if the provided string is not that of a
 	 *                                  standard rule.
-	 * @since v0.4.0
 	 * @since 2021-12-24
+	 * @since v0.4.0
 	 */
-	public static final Function<UncertainDouble, String> getStandardRule(
+	public static Function<UncertainDouble, String> getStandardRule(
 			String ruleToString) {
 		if (UNCERTAINTY_BASED_ROUNDING_RULE.toString().equals(ruleToString))
 			return UNCERTAINTY_BASED_ROUNDING_RULE;
@@ -230,13 +232,13 @@ public final class StandardDisplayRules {
 		final var placesMatch = FixedDecimals.TO_STRING_PATTERN
 				.matcher(ruleToString);
 		if (placesMatch.matches())
-			return new FixedDecimals(Integer.valueOf(placesMatch.group(1)));
+			return new FixedDecimals(Integer.parseInt(placesMatch.group(1)));
 
 		// test if it is a fixed-sig-fig rule
 		final var sigFigMatch = FixedPrecision.TO_STRING_PATTERN
 				.matcher(ruleToString);
 		if (sigFigMatch.matches())
-			return new FixedPrecision(Integer.valueOf(sigFigMatch.group(1)));
+			return new FixedPrecision(Integer.parseInt(sigFigMatch.group(1)));
 
 		throw new IllegalArgumentException(
 				"Provided string does not match any given rules.");
@@ -244,10 +246,10 @@ public final class StandardDisplayRules {
 
 	/**
 	 * @return an UncertainDouble-based rounding rule
-	 * @since v0.4.0
 	 * @since 2022-04-18
+	 * @since v0.4.0
 	 */
-	public static final UncertaintyBased uncertaintyBased() {
+	public static UncertaintyBased uncertaintyBased() {
 		return UNCERTAINTY_BASED_ROUNDING_RULE;
 	}
 
diff --git a/src/main/java/sevenUnitsGUI/TabbedView.java b/src/main/java/sevenUnitsGUI/TabbedView.java
index 997acc3..8be58f5 100644
--- a/src/main/java/sevenUnitsGUI/TabbedView.java
+++ b/src/main/java/sevenUnitsGUI/TabbedView.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022 Adrien Hopkins
+ * Copyright (C) 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -24,13 +24,16 @@ import java.awt.event.ItemEvent;
 import java.awt.event.KeyEvent;
 import java.util.AbstractSet;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
+import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.OptionalInt;
 import java.util.Set;
+import java.util.function.Consumer;
 import java.util.function.Function;
 
 import javax.swing.BorderFactory;
@@ -64,8 +67,8 @@ import sevenUnits.utils.UncertainDouble;
 /**
  * A View that separates its functions into multiple tabs
  *
- * @since v0.4.0
  * @since 2022-02-19
+ * @since v0.4.0
  */
 final class TabbedView implements ExpressionConversionView, UnitConversionView {
 	/**
@@ -73,8 +76,8 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 	 *
 	 * @param <E> type of item in list
 	 *
-	 * @since v0.4.0
 	 * @since 2022-02-19
+	 * @since v0.4.0
 	 */
 	private static final class JComboBoxItemSet<E> extends AbstractSet<E> {
 		private final JComboBox<E> comboBox;
@@ -82,6 +85,7 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 		/**
 		 * @param comboBox combo box to get items from
 		 * @since 2022-02-19
+		 * @since v0.4.0
 		 */
 		public JComboBoxItemSet(JComboBox<E> comboBox) {
 			this.comboBox = comboBox;
@@ -101,9 +105,8 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 				public E next() {
 					if (this.hasNext())
 						return JComboBoxItemSet.this.comboBox.getItemAt(this.index++);
-					else
-						throw new NoSuchElementException(
-								"Iterator has finished iteration");
+					throw new NoSuchElementException(
+							"Iterator has finished iteration");
 				}
 			};
 		}
@@ -119,10 +122,10 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 	 * The standard types of rounding, corresponding to the options on the
 	 * TabbedView's settings panel.
 	 *
-	 * @since v0.4.0
 	 * @since 2022-04-18
+	 * @since v0.4.0
 	 */
-	private static enum StandardRoundingType {
+	private enum StandardRoundingType {
 		/**
 		 * Rounds to a fixed number of significant digits. Precision is used,
 		 * representing the number of significant digits to round to.
@@ -144,8 +147,8 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 	 * Creates a TabbedView.
 	 *
 	 * @param args command line arguments
-	 * @since v0.4.0
 	 * @since 2022-02-19
+	 * @since v0.4.0
 	 */
 	public static void main(String[] args) {
 		// This view doesn't need to do anything, the side effects of creating it
@@ -195,15 +198,19 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 	/** The text box for prefix data in the prefix viewer */
 	private final JTextArea prefixTextBox;
 
-	// SETTINGS STUFF
+	// INFO & SETTINGS STUFF
+	final JTextArea infoTextArea;
+	private final JComboBox<String> localeSelector;
 	private StandardRoundingType roundingType;
 	private int precision;
 
+	private final Map<String, Consumer<String>> localizedTextSetters;
+
 	/**
 	 * Creates the view and makes it visible to the user
-	 * 
-	 * @since v0.4.0
+	 *
 	 * @since 2022-02-19
+	 * @since v0.4.0
 	 */
 	public TabbedView() {
 		// enable system look and feel
@@ -218,21 +225,25 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 
 		// initialize important components
 		this.presenter = new Presenter(this);
-		this.frame = new JFrame("7Units " + ProgramInfo.VERSION);
+		this.frame = new JFrame("7Units (Unlocalized)");
 		this.frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
 
 		// master components (those that contain everything else within them)
 		this.masterPane = new JTabbedPane();
 		this.frame.add(this.masterPane);
 
+		this.localizedTextSetters = new HashMap<>();
+
 		// ============ UNIT CONVERSION TAB ============
-		final JPanel convertUnitPanel = new JPanel();
+		final var convertUnitPanel = new JPanel();
 		this.masterPane.addTab("Convert Units", convertUnitPanel);
+		this.localizedTextSetters.put("tv.convert_units.title",
+				txt -> this.masterPane.setTitleAt(0, txt));
 		this.masterPane.setMnemonicAt(0, KeyEvent.VK_U);
 		convertUnitPanel.setLayout(new BorderLayout());
 
 		{ // panel for input part
-			final JPanel inputPanel = new JPanel();
+			final var inputPanel = new JPanel();
 			convertUnitPanel.add(inputPanel, BorderLayout.CENTER);
 			inputPanel.setLayout(new GridLayout(1, 3));
 			inputPanel.setBorder(new EmptyBorder(6, 6, 3, 6));
@@ -240,7 +251,7 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 			this.fromSearch = new SearchBoxList<>();
 			inputPanel.add(this.fromSearch);
 
-			final JPanel inBetweenPanel = new JPanel();
+			final var inBetweenPanel = new JPanel();
 			inputPanel.add(inBetweenPanel);
 			inBetweenPanel.setLayout(new BorderLayout());
 
@@ -249,7 +260,7 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 			this.dimensionSelector
 					.addItemListener(e -> this.presenter.updateView());
 
-			final JLabel arrowLabel = new JLabel("-->");
+			final var arrowLabel = new JLabel("-->");
 			inBetweenPanel.add(arrowLabel, BorderLayout.CENTER);
 			arrowLabel.setHorizontalAlignment(SwingConstants.CENTER);
 
@@ -258,12 +269,14 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 		}
 
 		{ // panel for submit and output, and also value entry
-			final JPanel outputPanel = new JPanel();
+			final var outputPanel = new JPanel();
 			convertUnitPanel.add(outputPanel, BorderLayout.PAGE_END);
 			outputPanel.setLayout(new BorderLayout());
 			outputPanel.setBorder(new EmptyBorder(3, 6, 6, 6));
 
-			final JLabel valuePrompt = new JLabel("Value to convert: ");
+			final var valuePrompt = new JLabel();
+			this.localizedTextSetters.put("tv.convert_units.value_prompt",
+					valuePrompt::setText);
 			outputPanel.add(valuePrompt, BorderLayout.LINE_START);
 
 			this.valueInput = new JTextField();
@@ -271,6 +284,8 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 
 			// conversion button
 			this.convertUnitButton = new JButton("Convert");
+			this.localizedTextSetters.put("tv.convert_units.convert_btn",
+					this.convertUnitButton::setText);
 			outputPanel.add(this.convertUnitButton, BorderLayout.LINE_END);
 			this.convertUnitButton
 					.addActionListener(e -> this.presenter.convertUnits());
@@ -283,23 +298,31 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 		}
 
 		// ============ EXPRESSION CONVERSION TAB ============
-		final JPanel convertExpressionPanel = new JPanel();
+		final var convertExpressionPanel = new JPanel();
 		this.masterPane.addTab("Convert Unit Expressions",
 				convertExpressionPanel);
+		this.localizedTextSetters.put("tv.convert_expressions.title",
+				txt -> this.masterPane.setTitleAt(1, txt));
 		this.masterPane.setMnemonicAt(1, KeyEvent.VK_E);
 		convertExpressionPanel.setLayout(new GridLayout(4, 1));
 
 		// from and to expressions
 		this.fromEntry = new JTextField();
 		convertExpressionPanel.add(this.fromEntry);
-		this.fromEntry.setBorder(BorderFactory.createTitledBorder("From"));
+		this.localizedTextSetters.put("tv.convert_expressions.from",
+				txt -> this.fromEntry
+						.setBorder(BorderFactory.createTitledBorder(txt)));
 
 		this.toEntry = new JTextField();
 		convertExpressionPanel.add(this.toEntry);
-		this.toEntry.setBorder(BorderFactory.createTitledBorder("To"));
+		this.localizedTextSetters.put("tv.convert_expressions.to",
+				txt -> this.toEntry
+						.setBorder(BorderFactory.createTitledBorder(txt)));
 
 		// button to convert
-		this.convertExpressionButton = new JButton("Convert");
+		this.convertExpressionButton = new JButton();
+		this.localizedTextSetters.put("tv.convert_expressions.convert_btn",
+				this.convertExpressionButton::setText);
 		convertExpressionPanel.add(this.convertExpressionButton);
 
 		this.convertExpressionButton
@@ -309,13 +332,16 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 		// output of conversion
 		this.expressionOutput = new JTextArea(2, 32);
 		convertExpressionPanel.add(this.expressionOutput);
-		this.expressionOutput
-				.setBorder(BorderFactory.createTitledBorder("Output"));
+		this.localizedTextSetters.put("tv.convert_expressions.output",
+				txt -> this.expressionOutput
+						.setBorder(BorderFactory.createTitledBorder(txt)));
 		this.expressionOutput.setEditable(false);
 
 		// =========== UNIT VIEWER ===========
-		final JPanel unitLookupPanel = new JPanel();
+		final var unitLookupPanel = new JPanel();
 		this.masterPane.addTab("Unit Viewer", unitLookupPanel);
+		this.localizedTextSetters.put("tv.unit_viewer.title",
+				txt -> this.masterPane.setTitleAt(2, txt));
 		this.masterPane.setMnemonicAt(2, KeyEvent.VK_V);
 		unitLookupPanel.setLayout(new GridLayout());
 
@@ -331,8 +357,10 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 		this.unitTextBox.setLineWrap(true);
 
 		// ============ PREFIX VIEWER =============
-		final JPanel prefixLookupPanel = new JPanel();
+		final var prefixLookupPanel = new JPanel();
 		this.masterPane.addTab("Prefix Viewer", prefixLookupPanel);
+		this.localizedTextSetters.put("tv.prefix_viewer.title",
+				txt -> this.masterPane.setTitleAt(3, txt));
 		this.masterPane.setMnemonicAt(3, KeyEvent.VK_P);
 		prefixLookupPanel.setLayout(new GridLayout(1, 2));
 
@@ -349,23 +377,24 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 
 		// ============ INFO PANEL ============
 
-		final JPanel infoPanel = new JPanel();
+		final var infoPanel = new JPanel();
 		this.masterPane.addTab("\uD83D\uDEC8", // info (i) character
 				new JScrollPane(infoPanel));
 
-		final JTextArea infoTextArea = new JTextArea();
-		infoTextArea.setEditable(false);
-		infoTextArea.setOpaque(false);
-		infoPanel.add(infoTextArea);
-		infoTextArea.setText(Presenter.getAboutText());
+		this.infoTextArea = new JTextArea();
+		this.infoTextArea.setEditable(false);
+		this.infoTextArea.setOpaque(false);
+		infoPanel.add(this.infoTextArea);
 
 		// ============ SETTINGS PANEL ============
+		this.localeSelector = new JComboBox<>();
 		this.masterPane.addTab("\u2699",
 				new JScrollPane(this.createSettingsPanel()));
 		this.masterPane.setMnemonicAt(5, KeyEvent.VK_S);
 
 		// ============ FINALIZE CREATION OF VIEW ============
 		this.presenter.postViewInitialize();
+		this.updateText();
 		this.frame.pack();
 		this.frame.setVisible(true);
 	}
@@ -375,40 +404,46 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 	 * code more organized, as this function is massive!)
 	 *
 	 * @since 2022-02-19
+	 * @since v0.4.0
 	 */
 	private JPanel createSettingsPanel() {
-		final JPanel settingsPanel = new JPanel();
+		final var settingsPanel = new JPanel();
 
 		settingsPanel
 				.setLayout(new BoxLayout(settingsPanel, BoxLayout.PAGE_AXIS));
 
 		// ============ ROUNDING SETTINGS ============
 		{
-			final JPanel roundingPanel = new JPanel();
+			final var roundingPanel = new JPanel();
 			settingsPanel.add(roundingPanel);
-			roundingPanel.setBorder(new TitledBorder("Rounding Settings"));
+			this.localizedTextSetters.put("tv.settings.rounding.title",
+					txt -> roundingPanel.setBorder(new TitledBorder(txt)));
 			roundingPanel.setLayout(new GridBagLayout());
 
 			// rounding rule selection
-			final ButtonGroup roundingRuleButtons = new ButtonGroup();
+			final var roundingRuleButtons = new ButtonGroup();
 			this.roundingType = this.getPresenterRoundingType()
 					.orElseThrow(() -> new AssertionError(
 							"Presenter loaded non-standard rounding rule"));
 			this.precision = this.getPresenterPrecision().orElse(6);
 
-			final JLabel roundingRuleLabel = new JLabel("Rounding Rule:");
+			final var roundingRuleLabel = new JLabel();
+			this.localizedTextSetters.put("tv.settings.rounding.rule",
+					roundingRuleLabel::setText);
 			roundingPanel.add(roundingRuleLabel, new GridBagBuilder(0, 0)
 					.setAnchor(GridBagConstraints.LINE_START).build());
 
 			// sigDigSlider needs to be first so that the rounding-type buttons can
 			// show and hide it
-			final JLabel sliderLabel = new JLabel("Precision:");
+			final var sliderLabel = new JLabel();
+			this.localizedTextSetters.put("tv.settings.rounding.precision",
+					sliderLabel::setText);
 			sliderLabel.setVisible(
 					this.roundingType != StandardRoundingType.UNCERTAINTY);
 			roundingPanel.add(sliderLabel, new GridBagBuilder(0, 4)
 					.setAnchor(GridBagConstraints.LINE_START).build());
 
-			final JSlider sigDigSlider = new JSlider(0, 12);
+			final var sigDigSlider = new JSlider(0, 12);
 			roundingPanel.add(sigDigSlider, new GridBagBuilder(0, 5)
 					.setAnchor(GridBagConstraints.LINE_START).build());
 
@@ -428,8 +463,9 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 			});
 
 			// significant digit rounding
-			final JRadioButton fixedPrecision = new JRadioButton(
-					"Fixed Precision");
+			final var fixedPrecision = new JRadioButton();
+			this.localizedTextSetters.put("tv.settings.rounding.fixed_sigfig",
+					fixedPrecision::setText);
 			if (this.roundingType == StandardRoundingType.SIGNIFICANT_DIGITS) {
 				fixedPrecision.setSelected(true);
 			}
@@ -444,8 +480,9 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 					.setAnchor(GridBagConstraints.LINE_START).build());
 
 			// decimal place rounding
-			final JRadioButton fixedDecimals = new JRadioButton(
-					"Fixed Decimal Places");
+			final var fixedDecimals = new JRadioButton();
+			this.localizedTextSetters.put("tv.settings.rounding.fixed_places",
+					fixedDecimals::setText);
 			if (this.roundingType == StandardRoundingType.DECIMAL_PLACES) {
 				fixedDecimals.setSelected(true);
 			}
@@ -460,8 +497,9 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 					.setAnchor(GridBagConstraints.LINE_START).build());
 
 			// scientific rounding
-			final JRadioButton relativePrecision = new JRadioButton(
-					"Uncertainty-Based Rounding");
+			final var relativePrecision = new JRadioButton();
+			this.localizedTextSetters.put("tv.settings.rounding.uncertainty",
+					relativePrecision::setText);
 			if (this.roundingType == StandardRoundingType.UNCERTAINTY) {
 				relativePrecision.setSelected(true);
 			}
@@ -478,10 +516,10 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 
 		// ============ PREFIX REPETITION SETTINGS ============
 		{
-			final JPanel prefixRepetitionPanel = new JPanel();
+			final var prefixRepetitionPanel = new JPanel();
 			settingsPanel.add(prefixRepetitionPanel);
-			prefixRepetitionPanel
-					.setBorder(new TitledBorder("Prefix Repetition Settings"));
+			this.localizedTextSetters.put("tv.settings.repetition.title",
+					txt -> prefixRepetitionPanel.setBorder(new TitledBorder(txt)));
 			prefixRepetitionPanel.setLayout(new GridBagLayout());
 
 			final var prefixRule = this.getPresenterPrefixRule()
@@ -489,9 +527,11 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 							"Presenter loaded non-standard prefix rule"));
 
 			// prefix rules
-			final ButtonGroup prefixRuleButtons = new ButtonGroup();
+			final var prefixRuleButtons = new ButtonGroup();
 
-			final JRadioButton noRepetition = new JRadioButton("No Repetition");
+			final var noRepetition = new JRadioButton();
+			this.localizedTextSetters.put("tv.settings.repetition.no",
+					noRepetition::setText);
 			if (prefixRule == DefaultPrefixRepetitionRule.NO_REPETITION) {
 				noRepetition.setSelected(true);
 			}
@@ -504,7 +544,9 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 			prefixRepetitionPanel.add(noRepetition, new GridBagBuilder(0, 0)
 					.setAnchor(GridBagConstraints.LINE_START).build());
 
-			final JRadioButton noRestriction = new JRadioButton("No Restriction");
+			final var noRestriction = new JRadioButton();
+			this.localizedTextSetters.put("tv.settings.repetition.any",
+					noRestriction::setText);
 			if (prefixRule == DefaultPrefixRepetitionRule.NO_RESTRICTION) {
 				noRestriction.setSelected(true);
 			}
@@ -517,8 +559,9 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 			prefixRepetitionPanel.add(noRestriction, new GridBagBuilder(0, 1)
 					.setAnchor(GridBagConstraints.LINE_START).build());
 
-			final JRadioButton customRepetition = new JRadioButton(
-					"Complex Repetition");
+			final var customRepetition = new JRadioButton();
+			this.localizedTextSetters.put("tv.settings.repetition.complex",
+					customRepetition::setText);
 			if (prefixRule == DefaultPrefixRepetitionRule.COMPLEX_REPETITION) {
 				customRepetition.setSelected(true);
 			}
@@ -534,18 +577,20 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 
 		// ============ SEARCH SETTINGS ============
 		{
-			final JPanel searchingPanel = new JPanel();
+			final var searchingPanel = new JPanel();
 			settingsPanel.add(searchingPanel);
-			searchingPanel.setBorder(new TitledBorder("Search Settings"));
+			this.localizedTextSetters.put("tv.settings.search.title",
+					txt -> searchingPanel.setBorder(new TitledBorder(txt)));
 			searchingPanel.setLayout(new GridBagLayout());
 
 			// searching rules
-			final ButtonGroup searchRuleButtons = new ButtonGroup();
+			final var searchRuleButtons = new ButtonGroup();
 
 			final var searchRule = this.presenter.getSearchRule();
 
-			final JRadioButton noPrefixes = new JRadioButton(
-					"Never Include Prefixed Units");
+			final var noPrefixes = new JRadioButton();
+			this.localizedTextSetters.put("tv.settings.search.no_prefixes",
+					noPrefixes::setText);
 			noPrefixes.addActionListener(e -> {
 				this.presenter.setSearchRule(PrefixSearchRule.NO_PREFIXES);
 				this.presenter.updateView();
@@ -555,8 +600,9 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 			searchingPanel.add(noPrefixes, new GridBagBuilder(0, 0)
 					.setAnchor(GridBagConstraints.LINE_START).build());
 
-			final JRadioButton commonPrefixes = new JRadioButton(
-					"Include Common Prefixes");
+			final var commonPrefixes = new JRadioButton();
+			this.localizedTextSetters.put("tv.settings.search.common_prefixes",
+					commonPrefixes::setText);
 			commonPrefixes.addActionListener(e -> {
 				this.presenter.setSearchRule(PrefixSearchRule.COMMON_PREFIXES);
 				this.presenter.updateView();
@@ -566,8 +612,9 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 			searchingPanel.add(commonPrefixes, new GridBagBuilder(0, 1)
 					.setAnchor(GridBagConstraints.LINE_START).build());
 
-			final JRadioButton alwaysInclude = new JRadioButton(
-					"Include All Single Prefixes");
+			final var alwaysInclude = new JRadioButton();
+			this.localizedTextSetters.put("tv.settings.search.all_prefixes",
+					alwaysInclude::setText);
 			alwaysInclude.addActionListener(e -> {
 				this.presenter
 						.setSearchRule(this.presenter.getUniversalSearchRule());
@@ -592,34 +639,66 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 
 		// ============ OTHER SETTINGS ============
 		{
-			final JPanel miscPanel = new JPanel();
+			final var miscPanel = new JPanel();
 			settingsPanel.add(miscPanel);
 			miscPanel.setLayout(new GridBagLayout());
 
-			final JCheckBox oneWay = new JCheckBox("Convert One Way Only");
+			final var oneWay = new JCheckBox();
+			this.localizedTextSetters.put("tv.settings.oneway", oneWay::setText);
 			oneWay.setSelected(this.presenter.oneWayConversionEnabled());
 			oneWay.addItemListener(e -> {
 				this.presenter.setOneWayConversionEnabled(
 						e.getStateChange() == ItemEvent.SELECTED);
 				this.presenter.saveSettings();
 			});
-			miscPanel.add(oneWay, new GridBagBuilder(0, 0)
+			miscPanel.add(oneWay, new GridBagBuilder(0, 0, 2, 1)
 					.setAnchor(GridBagConstraints.LINE_START).build());
 
-			final JCheckBox showAllVariations = new JCheckBox(
-					"Show Duplicate Units & Prefixes");
+			final var showAllVariations = new JCheckBox();
+			this.localizedTextSetters.put("tv.settings.show_duplicate",
+					showAllVariations::setText);
 			showAllVariations.setSelected(this.presenter.duplicatesShown());
 			showAllVariations.addItemListener(e -> {
 				this.presenter
 						.setShowDuplicates(e.getStateChange() == ItemEvent.SELECTED);
 				this.presenter.saveSettings();
 			});
-			miscPanel.add(showAllVariations, new GridBagBuilder(0, 1)
+			miscPanel.add(showAllVariations, new GridBagBuilder(0, 1, 2, 1)
+					.setAnchor(GridBagConstraints.LINE_START).build());
+
+			final var useDefaultFiles = new JCheckBox();
+			this.localizedTextSetters.put("tv.settings.use_default_files",
+					useDefaultFiles::setText);
+			useDefaultFiles.setSelected(this.presenter.usingDefaultDatafiles());
+			useDefaultFiles.addItemListener(e -> {
+				this.presenter.setUseDefaultDatafiles(
+						e.getStateChange() == ItemEvent.SELECTED);
+				this.presenter.saveSettings();
+			});
+			miscPanel.add(useDefaultFiles, new GridBagBuilder(0, 2, 2, 1)
 					.setAnchor(GridBagConstraints.LINE_START).build());
 
-			final JButton unitFileButton = new JButton("Manage Unit Data Files");
+			final var localeLabel = new JLabel();
+			this.localizedTextSetters.put("tv.settings.locale",
+					localeLabel::setText);
+			miscPanel.add(localeLabel, new GridBagBuilder(0, 3, 1, 1)
+					.setAnchor(GridBagConstraints.LINE_START).build());
+
+			this.presenter.getAvailableLocales().stream().sorted()
+					.forEachOrdered(this.localeSelector::addItem);
+			this.localeSelector.setSelectedItem(this.presenter.getUserLocale());
+			this.localeSelector.addItemListener(e -> {
+				this.presenter.setUserLocale((String) e.getItem());
+				this.presenter.saveSettings();
+			});
+			miscPanel.add(localeSelector, new GridBagBuilder(1, 3, 1, 1)
+					.setAnchor(GridBagConstraints.LINE_END).build());
+
+			final var unitFileButton = new JButton();
+			this.localizedTextSetters.put("tv.settings.unitfiles.button",
+					unitFileButton::setText);
 			unitFileButton.setEnabled(false);
-			miscPanel.add(unitFileButton, new GridBagBuilder(0, 2)
+			miscPanel.add(unitFileButton, new GridBagBuilder(0, 4, 2, 1)
 					.setAnchor(GridBagConstraints.LINE_START).build());
 		}
 
@@ -662,8 +741,8 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 	/**
 	 * @return the precision of the presenter's rounding rule, if that is
 	 *         meaningful
-	 * @since v0.4.0
 	 * @since 2022-04-18
+	 * @since v0.4.0
 	 */
 	private OptionalInt getPresenterPrecision() {
 		final var presenterRule = this.presenter.getNumberDisplayRule();
@@ -671,18 +750,17 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 			return OptionalInt
 					.of(((StandardDisplayRules.FixedDecimals) presenterRule)
 							.decimalPlaces());
-		else if (presenterRule instanceof StandardDisplayRules.FixedPrecision)
+		if (presenterRule instanceof StandardDisplayRules.FixedPrecision)
 			return OptionalInt
 					.of(((StandardDisplayRules.FixedPrecision) presenterRule)
 							.significantFigures());
-		else
-			return OptionalInt.empty();
+		return OptionalInt.empty();
 	}
 
 	/**
 	 * @return presenter's prefix repetition rule
-	 * @since v0.4.0
 	 * @since 2022-04-19
+	 * @since v0.4.0
 	 */
 	private Optional<DefaultPrefixRepetitionRule> getPresenterPrefixRule() {
 		final var prefixRule = this.presenter.getPrefixRepetitionRule();
@@ -694,25 +772,24 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 	/**
 	 * Determines which rounding type the presenter is currently using, if any.
 	 *
-	 * @since v0.4.0
 	 * @since 2022-04-18
+	 * @since v0.4.0
 	 */
 	private Optional<StandardRoundingType> getPresenterRoundingType() {
 		final var presenterRule = this.presenter.getNumberDisplayRule();
 		if (Objects.equals(presenterRule,
 				StandardDisplayRules.uncertaintyBased()))
 			return Optional.of(StandardRoundingType.UNCERTAINTY);
-		else if (presenterRule instanceof StandardDisplayRules.FixedDecimals)
+		if (presenterRule instanceof StandardDisplayRules.FixedDecimals)
 			return Optional.of(StandardRoundingType.DECIMAL_PLACES);
-		else if (presenterRule instanceof StandardDisplayRules.FixedPrecision)
+		if (presenterRule instanceof StandardDisplayRules.FixedPrecision)
 			return Optional.of(StandardRoundingType.SIGNIFICANT_DIGITS);
-		else
-			return Optional.empty();
+		return Optional.empty();
 	}
 
 	@Override
 	public Optional<String> getSelectedDimensionName() {
-		final String selectedItem = (String) this.dimensionSelector
+		final var selectedItem = (String) this.dimensionSelector
 				.getSelectedItem();
 		return Optional.ofNullable(selectedItem);
 	}
@@ -780,8 +857,7 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 
 	@Override
 	public void showExpressionConversionOutput(UnitConversionRecord uc) {
-		this.expressionOutput.setText(String.format("%s = %s %s", uc.fromName(),
-				uc.outputValueString(), uc.toName()));
+		this.expressionOutput.setText(uc.toString());
 	}
 
 	@Override
@@ -806,9 +882,9 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 	/**
 	 * Sets the presenter's rounding rule to the one specified by the current
 	 * settings
-	 * 
-	 * @since v0.4.0
+	 *
 	 * @since 2022-04-18
+	 * @since v0.4.0
 	 */
 	private void updatePresenterRoundingRule() {
 		final Function<UncertainDouble, String> roundingRule;
@@ -828,4 +904,13 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 		this.presenter.setNumberDisplayRule(roundingRule);
 		this.presenter.saveSettings();
 	}
+
+	@Override
+	public void updateText() {
+		this.frame.setTitle(this.presenter.getLocalizedText("tv.title")
+				.replace("[v]", ProgramInfo.VERSION.toString()));
+		this.infoTextArea.setText(this.presenter.getAboutText());
+		this.localizedTextSetters.forEach(
+				(id, action) -> action.accept(this.presenter.getLocalizedText(id)));
+	}
 }
diff --git a/src/main/java/sevenUnitsGUI/UnitConversionRecord.java b/src/main/java/sevenUnitsGUI/UnitConversionRecord.java
index 43a62e6..3c2bb6c 100644
--- a/src/main/java/sevenUnitsGUI/UnitConversionRecord.java
+++ b/src/main/java/sevenUnitsGUI/UnitConversionRecord.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022 Adrien Hopkins
+ * Copyright (C) 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -24,18 +24,18 @@ import sevenUnits.unit.UnitValue;
 /**
  * A record of a conversion between units or expressions
  *
- * @since v0.4.0
  * @since 2022-04-09
+ * @since v0.4.0
  */
 public final class UnitConversionRecord {
 	/**
 	 * Gets a {@code UnitConversionRecord} from two linear unit values
 	 *
-	 * @param input  input unit & value
-	 * @param output output unit & value
+	 * @param input  input unit &amp; value
+	 * @param output output unit &amp; value
 	 * @return unit conversion record
-	 * @since v0.4.0
 	 * @since 2022-04-09
+	 * @since v0.4.0
 	 */
 	public static UnitConversionRecord fromLinearValues(LinearUnitValue input,
 			LinearUnitValue output) {
@@ -48,11 +48,11 @@ public final class UnitConversionRecord {
 	/**
 	 * Gets a {@code UnitConversionRecord} from two unit values
 	 *
-	 * @param input  input unit & value
-	 * @param output output unit & value
+	 * @param input  input unit &amp; value
+	 * @param output output unit &amp; value
 	 * @return unit conversion record
-	 * @since v0.4.0
 	 * @since 2022-04-09
+	 * @since v0.4.0
 	 */
 	public static UnitConversionRecord fromValues(UnitValue input,
 			UnitValue output) {
@@ -70,8 +70,8 @@ public final class UnitConversionRecord {
 	 * @param inputValueString  string representing input value
 	 * @param outputValueString string representing output value
 	 * @return unit conversion record
-	 * @since v0.4.0
 	 * @since 2022-04-09
+	 * @since v0.4.0
 	 */
 	public static UnitConversionRecord valueOf(String fromName, String toName,
 			String inputValueString, String outputValueString) {
@@ -79,13 +79,9 @@ public final class UnitConversionRecord {
 				outputValueString);
 	}
 
-	/**
-	 * The name of the unit or expression that was converted from
-	 */
+	/** The name of the unit or expression that was converted from */
 	private final String fromName;
-	/**
-	 * The name of the unit or expression that was converted to
-	 */
+	/** The name of the unit or expression that was converted to */
 	private final String toName;
 
 	/**
@@ -106,6 +102,7 @@ public final class UnitConversionRecord {
 	 * @param inputValueString  string representing input value
 	 * @param outputValueString string representing output value
 	 * @since 2022-04-09
+	 * @since v0.4.0
 	 */
 	private UnitConversionRecord(String fromName, String toName,
 			String inputValueString, String outputValueString) {
@@ -121,7 +118,7 @@ public final class UnitConversionRecord {
 			return true;
 		if (!(obj instanceof UnitConversionRecord))
 			return false;
-		final UnitConversionRecord other = (UnitConversionRecord) obj;
+		final var other = (UnitConversionRecord) obj;
 		if (this.fromName == null) {
 			if (other.fromName != null)
 				return false;
@@ -147,8 +144,8 @@ public final class UnitConversionRecord {
 
 	/**
 	 * @return name of unit or expression that was converted from
-	 * @since v0.4.0
 	 * @since 2022-04-09
+	 * @since v0.4.0
 	 */
 	public String fromName() {
 		return this.fromName;
@@ -156,8 +153,8 @@ public final class UnitConversionRecord {
 
 	@Override
 	public int hashCode() {
-		final int prime = 31;
-		int result = 1;
+		final var prime = 31;
+		var result = 1;
 		result = prime * result
 				+ (this.fromName == null ? 0 : this.fromName.hashCode());
 		result = prime * result + (this.inputValueString == null ? 0
@@ -171,8 +168,8 @@ public final class UnitConversionRecord {
 
 	/**
 	 * @return string representing input value
-	 * @since v0.4.0
 	 * @since 2022-04-09
+	 * @since v0.4.0
 	 */
 	public String inputValueString() {
 		return this.inputValueString;
@@ -180,8 +177,8 @@ public final class UnitConversionRecord {
 
 	/**
 	 * @return string representing output value
-	 * @since v0.4.0
 	 * @since 2022-04-09
+	 * @since v0.4.0
 	 */
 	public String outputValueString() {
 		return this.outputValueString;
@@ -189,8 +186,8 @@ public final class UnitConversionRecord {
 
 	/**
 	 * @return name of unit or expression that was converted to
-	 * @since v0.4.0
 	 * @since 2022-04-09
+	 * @since v0.4.0
 	 */
 	public String toName() {
 		return this.toName;
@@ -198,9 +195,9 @@ public final class UnitConversionRecord {
 
 	@Override
 	public String toString() {
-		final String inputString = this.inputValueString.isBlank() ? this.fromName
+		final var inputString = this.inputValueString.isBlank() ? this.fromName
 				: this.inputValueString + " " + this.fromName;
-		final String outputString = this.outputValueString.isBlank() ? this.toName
+		final var outputString = this.outputValueString.isBlank() ? this.toName
 				: this.outputValueString + " " + this.toName;
 		return inputString + " = " + outputString;
 	}
diff --git a/src/main/java/sevenUnitsGUI/UnitConversionView.java b/src/main/java/sevenUnitsGUI/UnitConversionView.java
index b9077f7..fa3a388 100644
--- a/src/main/java/sevenUnitsGUI/UnitConversionView.java
+++ b/src/main/java/sevenUnitsGUI/UnitConversionView.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2021-2022 Adrien Hopkins
+ * Copyright (C) 2021, 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -21,59 +21,59 @@ import java.util.Set;
 
 /**
  * A View that supports single unit-based conversion
- * 
+ *
  * @author Adrien Hopkins
- * @since v0.4.0
  * @since 2021-12-15
+ * @since v0.4.0
  */
 public interface UnitConversionView extends View {
 	/**
 	 * @return dimensions available for filtering
-	 * @since v0.4.0
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	Set<String> getDimensionNames();
 
 	/**
 	 * @return name of unit to convert <em>from</em>
-	 * @since v0.4.0
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	Optional<String> getFromSelection();
 
 	/**
 	 * @return list of names of units available to convert from
-	 * @since v0.4.0
 	 * @since 2022-03-30
+	 * @since v0.4.0
 	 */
 	Set<String> getFromUnitNames();
 
 	/**
 	 * @return value to convert between the units (specifically, the numeric
 	 *         string provided by the user)
-	 * @since v0.4.0
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	String getInputValue();
 
 	/**
 	 * @return selected dimension
-	 * @since v0.4.0
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	Optional<String> getSelectedDimensionName();
 
 	/**
 	 * @return name of unit to convert <em>to</em>
-	 * @since v0.4.0
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	Optional<String> getToSelection();
 
 	/**
 	 * @return list of names of units available to convert to
-	 * @since v0.4.0
 	 * @since 2022-03-30
+	 * @since v0.4.0
 	 */
 	Set<String> getToUnitNames();
 
@@ -81,8 +81,8 @@ public interface UnitConversionView extends View {
 	 * Sets the available dimensions for filtering.
 	 *
 	 * @param dimensionNames names of dimensions to use
-	 * @since v0.4.0
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	void setDimensionNames(Set<String> dimensionNames);
 
@@ -92,8 +92,8 @@ public interface UnitConversionView extends View {
 	 * that allow the user to select units from a list.
 	 *
 	 * @param unitNames names of units to convert from
-	 * @since v0.4.0
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	void setFromUnitNames(Set<String> unitNames);
 
@@ -103,18 +103,17 @@ public interface UnitConversionView extends View {
 	 * that allow the user to select units from a list.
 	 *
 	 * @param unitNames names of units to convert to
-	 * @since v0.4.0
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	void setToUnitNames(Set<String> unitNames);
 
 	/**
 	 * Shows the output of a unit conversion.
-	 * 
-	 * @param input  input unit & value (obtained from this view)
-	 * @param output output unit & value
-	 * @since v0.4.0
+	 *
+	 * @param uc record of unit conversion
 	 * @since 2021-12-24
+	 * @since v0.4.0
 	 */
 	void showUnitConversionOutput(UnitConversionRecord uc);
 }
diff --git a/src/main/java/sevenUnitsGUI/View.java b/src/main/java/sevenUnitsGUI/View.java
index 7dd0c44..0adeb3a 100644
--- a/src/main/java/sevenUnitsGUI/View.java
+++ b/src/main/java/sevenUnitsGUI/View.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2021-2022 Adrien Hopkins
+ * Copyright (C) 2021, 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -24,16 +24,16 @@ import sevenUnits.utils.NameSymbol;
 
 /**
  * An object that controls user interaction with 7Units
- * 
+ *
  * @author Adrien Hopkins
- * @since v0.4.0
  * @since 2021-12-15
+ * @since v0.4.0
  */
 public interface View {
 	/**
 	 * @return a new tabbed view
-	 * @since v0.4.0
 	 * @since 2022-04-19
+	 * @since v0.4.0
 	 */
 	static View createTabbedView() {
 		return new TabbedView();
@@ -41,22 +41,22 @@ public interface View {
 
 	/**
 	 * @return the presenter associated with this view
-	 * @since v0.4.0
 	 * @since 2022-04-19
+	 * @since v0.4.0
 	 */
 	Presenter getPresenter();
 
 	/**
 	 * @return name of prefix currently being viewed
-	 * @since v0.4.0
 	 * @since 2022-04-10
+	 * @since v0.4.0
 	 */
 	Optional<String> getViewedPrefixName();
 
 	/**
 	 * @return name of unit currently being viewed
-	 * @since v0.4.0
 	 * @since 2022-04-10
+	 * @since v0.4.0
 	 */
 	Optional<String> getViewedUnitName();
 
@@ -65,8 +65,8 @@ public interface View {
 	 * viewer
 	 *
 	 * @param prefixNames prefix names to view
-	 * @since v0.4.0
 	 * @since 2022-04-10
+	 * @since v0.4.0
 	 */
 	void setViewablePrefixNames(Set<String> prefixNames);
 
@@ -74,8 +74,8 @@ public interface View {
 	 * Sets the list of units that are available to be viewed in a unit viewer
 	 *
 	 * @param unitNames unit names to view
-	 * @since v0.4.0
 	 * @since 2022-04-10
+	 * @since v0.4.0
 	 */
 	void setViewableUnitNames(Set<String> unitNames);
 
@@ -85,8 +85,8 @@ public interface View {
 	 * @param title   title of error message; on any view that uses an error
 	 *                dialog, this should be the title of the error dialog.
 	 * @param message error message
-	 * @since v0.4.0
 	 * @since 2021-12-15
+	 * @since v0.4.0
 	 */
 	void showErrorMessage(String title, String message);
 
@@ -95,8 +95,8 @@ public interface View {
 	 *
 	 * @param name             name(s) and symbol of prefix
 	 * @param multiplierString string representation of prefix multiplier
-	 * @since v0.4.0
 	 * @since 2022-04-10
+	 * @since v0.4.0
 	 */
 	void showPrefix(NameSymbol name, String multiplierString);
 
@@ -107,9 +107,16 @@ public interface View {
 	 * @param definition    unit's definition string
 	 * @param dimensionName name of unit's dimension
 	 * @param type          type of unit (metric/semi-metric/non-metric)
-	 * @since v0.4.0
 	 * @since 2022-04-10
+	 * @since v0.4.0
 	 */
 	void showUnit(NameSymbol name, String definition, String dimensionName,
 			UnitType type);
+
+	/**
+	 * Updates the view's text to reflect the presenter's locale.
+	 *
+	 * This method <b>must not</b> call {@link Presenter#setUserLocale(String)}.
+	 */
+	void updateText();
 }
diff --git a/src/main/java/sevenUnitsGUI/ViewBot.java b/src/main/java/sevenUnitsGUI/ViewBot.java
index e6593fb..750e2d9 100644
--- a/src/main/java/sevenUnitsGUI/ViewBot.java
+++ b/src/main/java/sevenUnitsGUI/ViewBot.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022 Adrien Hopkins
+ * Copyright (C) 2022, 2024, 2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -30,10 +30,10 @@ import sevenUnits.utils.Nameable;
 /**
  * A class that simulates a View (supports both unit and expression conversion)
  * for testing. Getters and setters work as expected.
- * 
+ *
  * @author Adrien Hopkins
- * @since v0.4.0
  * @since 2022-01-29
+ * @since v0.4.0
  */
 public final class ViewBot
 		implements UnitConversionView, ExpressionConversionView {
@@ -42,6 +42,7 @@ public final class ViewBot
 	 * {@link View#showPrefix(NameSymbol, String)}, for testing.
 	 *
 	 * @since 2022-04-16
+	 * @since v0.4.0
 	 */
 	public static final class PrefixViewingRecord implements Nameable {
 		private final NameSymbol nameSymbol;
@@ -51,6 +52,7 @@ public final class ViewBot
 		 * @param nameSymbol
 		 * @param multiplierString
 		 * @since 2022-04-16
+		 * @since v0.4.0
 		 */
 		public PrefixViewingRecord(NameSymbol nameSymbol,
 				String multiplierString) {
@@ -64,7 +66,7 @@ public final class ViewBot
 				return true;
 			if (!(obj instanceof PrefixViewingRecord))
 				return false;
-			final PrefixViewingRecord other = (PrefixViewingRecord) obj;
+			final var other = (PrefixViewingRecord) obj;
 			return Objects.equals(this.multiplierString, other.multiplierString)
 					&& Objects.equals(this.nameSymbol, other.nameSymbol);
 		}
@@ -79,17 +81,19 @@ public final class ViewBot
 			return Objects.hash(this.multiplierString, this.nameSymbol);
 		}
 
+		/** @return A string representation of the prefix multiplier. */
 		public String multiplierString() {
 			return this.multiplierString;
 		}
 
+		/** @return A {@code NameSymbol} describing the prefix. */
 		public NameSymbol nameSymbol() {
 			return this.nameSymbol;
 		}
 
 		@Override
 		public String toString() {
-			final StringBuilder builder = new StringBuilder();
+			final var builder = new StringBuilder();
 			builder.append("PrefixViewingRecord [nameSymbol=");
 			builder.append(this.nameSymbol);
 			builder.append(", multiplierString=");
@@ -104,6 +108,7 @@ public final class ViewBot
 	 * {@link View#showUnit(NameSymbol, String, String, UnitType)}, for testing.
 	 *
 	 * @since 2022-04-16
+	 * @since v0.4.0
 	 */
 	public static final class UnitViewingRecord implements Nameable {
 		private final NameSymbol nameSymbol;
@@ -112,7 +117,12 @@ public final class ViewBot
 		private final UnitType unitType;
 
 		/**
+		 * @param nameSymbol    name(s) and symbol of unit
+		 * @param definition    unit's definition string
+		 * @param dimensionName name of unit's dimension
+		 * @param unitType      type of unit (metric/semi-metric/non-metric)
 		 * @since 2022-04-16
+		 * @since v0.4.0
 		 */
 		public UnitViewingRecord(NameSymbol nameSymbol, String definition,
 				String dimensionName, UnitType unitType) {
@@ -125,6 +135,7 @@ public final class ViewBot
 		/**
 		 * @return the definition
 		 * @since 2022-04-16
+		 * @since v0.4.0
 		 */
 		public String definition() {
 			return this.definition;
@@ -133,6 +144,7 @@ public final class ViewBot
 		/**
 		 * @return the dimensionName
 		 * @since 2022-04-16
+		 * @since v0.4.0
 		 */
 		public String dimensionName() {
 			return this.dimensionName;
@@ -144,7 +156,7 @@ public final class ViewBot
 				return true;
 			if (!(obj instanceof UnitViewingRecord))
 				return false;
-			final UnitViewingRecord other = (UnitViewingRecord) obj;
+			final var other = (UnitViewingRecord) obj;
 			return Objects.equals(this.definition, other.definition)
 					&& Objects.equals(this.dimensionName, other.dimensionName)
 					&& Objects.equals(this.nameSymbol, other.nameSymbol)
@@ -154,6 +166,7 @@ public final class ViewBot
 		/**
 		 * @return the nameSymbol
 		 * @since 2022-04-16
+		 * @since v0.4.0
 		 */
 		@Override
 		public NameSymbol getNameSymbol() {
@@ -166,13 +179,14 @@ public final class ViewBot
 					this.nameSymbol, this.unitType);
 		}
 
+		/** @return name(s) and symbol of unit */
 		public NameSymbol nameSymbol() {
 			return this.nameSymbol;
 		}
 
 		@Override
 		public String toString() {
-			final StringBuilder builder = new StringBuilder();
+			final var builder = new StringBuilder();
 			builder.append("UnitViewingRecord [nameSymbol=");
 			builder.append(this.nameSymbol);
 			builder.append(", definition=");
@@ -188,6 +202,7 @@ public final class ViewBot
 		/**
 		 * @return the unitType
 		 * @since 2022-04-16
+		 * @since v0.4.0
 		 */
 		public UnitType unitType() {
 			return this.unitType;
@@ -236,6 +251,7 @@ public final class ViewBot
 	 * Creates a new {@code ViewBot} with a new presenter.
 	 *
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	public ViewBot() {
 		this.presenter = new Presenter(this);
@@ -249,6 +265,7 @@ public final class ViewBot
 	/**
 	 * @return list of records of expression conversions done by this bot
 	 * @since 2022-04-09
+	 * @since v0.4.0
 	 */
 	public List<UnitConversionRecord> expressionConversionList() {
 		return Collections.unmodifiableList(this.expressionConversions);
@@ -257,6 +274,7 @@ public final class ViewBot
 	/**
 	 * @return the available dimensions
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	@Override
 	public Set<String> getDimensionNames() {
@@ -276,6 +294,7 @@ public final class ViewBot
 	/**
 	 * @return the units available for selection in From
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	@Override
 	public Set<String> getFromUnitNames() {
@@ -290,6 +309,7 @@ public final class ViewBot
 	/**
 	 * @return the presenter associated with tihs view
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	@Override
 	public Presenter getPresenter() {
@@ -314,6 +334,7 @@ public final class ViewBot
 	/**
 	 * @return the units available for selection in To
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	@Override
 	public Set<String> getToUnitNames() {
@@ -333,6 +354,7 @@ public final class ViewBot
 	/**
 	 * @return list of records of this viewBot's prefix views
 	 * @since 2022-04-16
+	 * @since v0.4.0
 	 */
 	public List<PrefixViewingRecord> prefixViewList() {
 		return Collections.unmodifiableList(this.prefixViewingRecords);
@@ -350,6 +372,7 @@ public final class ViewBot
 	 * @param fromExpression the expression to convert from
 	 * @throws NullPointerException if {@code fromExpression} is null
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	public void setFromExpression(String fromExpression) {
 		this.fromExpression = Objects.requireNonNull(fromExpression,
@@ -359,6 +382,7 @@ public final class ViewBot
 	/**
 	 * @param fromSelection the fromSelection to set
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	public void setFromSelection(Optional<String> fromSelection) {
 		this.fromSelection = Objects.requireNonNull(fromSelection,
@@ -368,6 +392,7 @@ public final class ViewBot
 	/**
 	 * @param fromSelection the fromSelection to set
 	 * @since 2022-02-10
+	 * @since v0.4.0
 	 */
 	public void setFromSelection(String fromSelection) {
 		this.setFromSelection(Optional.of(fromSelection));
@@ -381,20 +406,27 @@ public final class ViewBot
 	/**
 	 * @param inputValue the inputValue to set
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	public void setInputValue(String inputValue) {
 		this.inputValue = inputValue;
 	}
 
 	/**
-	 * @param selectedDimension the selectedDimension to set
+	 * @param selectedDimensionName the selectedDimensionName to set
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	public void setSelectedDimensionName(
 			Optional<String> selectedDimensionName) {
 		this.selectedDimensionName = selectedDimensionName;
 	}
 
+	/**
+	 * Sets the view's selected dimension
+	 *
+	 * @param selectedDimensionName name of dimension to select (string)
+	 */
 	public void setSelectedDimensionName(String selectedDimensionName) {
 		this.setSelectedDimensionName(Optional.of(selectedDimensionName));
 	}
@@ -405,6 +437,7 @@ public final class ViewBot
 	 * @param toExpression the expression to convert to
 	 * @throws NullPointerException if {@code toExpression} is null
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	public void setToExpression(String toExpression) {
 		this.toExpression = Objects.requireNonNull(toExpression,
@@ -412,14 +445,16 @@ public final class ViewBot
 	}
 
 	/**
-	 * @param toSelection the toSelection to set
+	 * @param toSelection unit set in the 'To' selection
 	 * @since 2022-01-29
+	 * @since v0.4.0
 	 */
 	public void setToSelection(Optional<String> toSelection) {
 		this.toSelection = Objects.requireNonNull(toSelection,
 				"toSelection cannot be null.");
 	}
 
+	/** @param toSelection unit set in the 'To' selection */
 	public void setToSelection(String toSelection) {
 		this.setToSelection(Optional.of(toSelection));
 	}
@@ -439,18 +474,28 @@ public final class ViewBot
 		// do nothing, ViewBot supports selecting any unit
 	}
 
+	/** @param viewedPrefixName name of prefix being used */
 	public void setViewedPrefixName(Optional<String> viewedPrefixName) {
 		this.prefixViewerSelection = viewedPrefixName;
 	}
 
+	/**
+	 * @param viewedPrefixName name of prefix being used (may not be null)
+	 * @throws NullPointerException if {@code viewedPrefixName} is null
+	 */
 	public void setViewedPrefixName(String viewedPrefixName) {
 		this.setViewedPrefixName(Optional.of(viewedPrefixName));
 	}
 
+	/** @param viewedUnitName name of unit being used */
 	public void setViewedUnitName(Optional<String> viewedUnitName) {
 		this.unitViewerSelection = viewedUnitName;
 	}
 
+	/**
+	 * @param viewedUnitName name of unit being used (may not be null)
+	 * @throws NullPointerException if {@code viewedUnitName} is null
+	 */
 	public void setViewedUnitName(String viewedUnitName) {
 		this.setViewedUnitName(Optional.of(viewedUnitName));
 	}
@@ -493,6 +538,7 @@ public final class ViewBot
 	/**
 	 * @return list of records of every unit conversion made by this bot
 	 * @since 2022-04-09
+	 * @since v0.4.0
 	 */
 	public List<UnitConversionRecord> unitConversionList() {
 		return Collections.unmodifiableList(this.unitConversions);
@@ -501,8 +547,14 @@ public final class ViewBot
 	/**
 	 * @return list of records of unit viewings made by this bot
 	 * @since 2022-04-16
+	 * @since v0.4.0
 	 */
 	public List<UnitViewingRecord> unitViewList() {
 		return Collections.unmodifiableList(this.unitViewingRecords);
 	}
+
+	@Override
+	public void updateText() {
+		// do nothing, since ViewBot is not localized
+	}
 }
diff --git a/src/main/java/sevenUnitsGUI/package-info.java b/src/main/java/sevenUnitsGUI/package-info.java
index cff1ded..9432960 100644
--- a/src/main/java/sevenUnitsGUI/package-info.java
+++ b/src/main/java/sevenUnitsGUI/package-info.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2021 Adrien Hopkins
+ * Copyright (C) 2021-2025 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -16,8 +16,9 @@
  */
 /**
  * The MVP GUI of SevenUnits
- * 
+ *
  * @author Adrien Hopkins
  * @since 2021-12-15
+ * @since v0.4.0
  */
 package sevenUnitsGUI;
\ No newline at end of file