Wrote user manual appendices, rewrote README to reflect user manual

1 files changed, 8 insertions, 2 deletions

diff --git a/docs/manual.org b/docs/manual.org
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--- a/docs/manual.org
+++ b/docs/manual.org
@@ -1,6 +1,6 @@
 #+TITLE: 7Units User Manual
 #+SUBTITLE: For Version 0.3.1
-#+DATE: 2021 July 2
+#+DATE: 2021 July 6
 #+LaTeX_HEADER: \usepackage[a4paper, lmargin=25mm, rmargin=25mm, tmargin=25mm, bmargin=25mm]{geometry}
 
 #+LaTeX: \newpage
@@ -68,10 +68,16 @@
 ** Miscellaneous Settings
     - Convert One Way Only :: In the simple conversion tab, only imperial/customary units will be shown on the left, and only metric units[fn:1] will be shown on the right.  Units listed in the exceptions file (~src/main/resources/metric_exceptions.txt~) will be shown on both sides.  This is a way to reduce the number of options you must search through if you only convert one way.  The expressions tab is unaffected.
     - Show Duplicates in "Convert Units" :: If unchecked, any unit that has multiple names will only have one included in the Convert Units lists.  The selected name will be the longest; if there are multiple longest names one is selected arbitrarily.  You will still be able to use these alternate names in the expressions tab.
-* Customizing 7Units
 * Appendices
 ** Unit Expressions
+   A unit expression is simply a math expression where the values being operated on are units or numbers.  The operations that can be used are (in order of precedence):
+   - Exponentiation (^); the exponent must be an integer.  Both units and numbers can be raised to an exponent
+   - Multiplication (*) and division (/).  Multiplication can also be done with a space (so "15 meter" is the same thing as "15 * meter").
+   - Addition (+) and subtraction (-).  They can only be done between units of the same dimension (measuring the same thing).  So you can add metres, inches and feet together, and you can add joules and calories together, but you can't add metres to seconds, or feet to calories, or watts to pounds.
 
+  Brackets can be used to manipulate the order of operations, and nonlinear units like Celsius and Fahrenheit cannot be used in expressions.  You can use a value in a nonlinear unit by putting brackets after it - for example, degC(12) represents the value 12 \deg C
+** Other Expressions
+   There are also a simplified version of expressions for prefixes and dimensions.  Only multiplication, division and exponentation are supported.  Currently, exponentation is not supported for dimensions, but that may be fixed in the future.
 * Footnotes
 
 [fn:1] 7Units's definition of "metric" is stricter than the SI, but all of the common units that are commonly considered metric but not included in 7Units's definition are included in the exceptions file.