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+
+# Commands
+
+<!-- md-toc-begin -->
+  * [About](#about)
+  * [Advanced interpreter](#advanced-interpreter)
+    * [piping](#piping)
+    * [command substitution](#command-substitution)
+    * [command splitting](#command-splitting)
+    * [advanced $variable interpolation](#advanced-variable-interpolation)
+    * [inline commands](#inline-commands)
+  * [Types of commands](#types-of-commands)
+    * [Built-in commands](#built-in-commands)
+      * [Plugins](#plugins)
+    * [Factoids](#factoids)
+      * [Code Factoids](#code-factoids)
+      * [Modules](#modules)
+  * [Command documentation](#command-documentation)
+    * [Administrative commands](#administrative-commands)
+    * [Channel management commands](#channel-management-commands)
+    * [Miscellaneous commands](#miscellaneous-commands)
+<!-- md-toc-end -->
+
+## About
+
+PBot has an advanced interpreter and several useful core built-in commands.
+
+## Advanced interpreter
+
+PBot has an advanced command interpreter with useful functionality.
+
+### piping
+
+You can pipe output from one command as input into another command, indefinitely.
+
+    <pragma-> !echo hello world | {sed s/world/everybody/} | {uc}
+       <PBot> HELLO EVERYBODY
+
+### command substitution
+
+You can insert the output from another command at any point within a command. This
+substitutes the command with its output at the point where the command was used.
+
+    <pragma-> !echo This is &{echo a demonstration} of command substitution
+       <PBot> This is a demonstration of command substitution
+
+For example, suppose you want to make a Google Image Search command. The naive
+way would be to simply do:
+
+    <pragma-> !factadd img /call echo https://google.com/search?tbm=isch&q=$args
+
+Unfortuately this would not support queries containing spaces or certain symbols. But
+never fear! We can use command substitution and the `uri_escape` function from the
+`func` command.
+
+Note that you must escape the command substitution to insert it literally into the
+factoid otherwise it will be expanded first.
+
+    <pragma-> !factadd img /call echo https://google.com/search?tbm=isch&q=\&{func uri_escape $args}
+
+    <pragma-> !img spaces & stuff
+       <PBot> https://google.com/search?tbm=isch&q=spaces%20%26%20stuff
+
+### command splitting
+
+You can execute multiple commands sequentially as one command.
+
+    <pragma-> !echo Test! ;;; me smiles. ;;; version
+       <PBot> Test! * PBot smiles. PBot version 2696 2020-01-04
+
+### advanced $variable interpolation
+
+You can use factoids as variables and interpolate them within commands.
+
+    <pragma-> !factadd greeting "Hello, world"
+
+    <pragma-> !echo greeting is $greeting
+       <PBot> greeting is Hello, world
+
+PBot variable interpolation supports [expansion modifiers](doc/Factoids.md#expansion-modifiers), which can be chained to
+combine their effects.
+
+    <pragma-> !echo $greeting:uc
+       <PBot> HELLO, WORLD
+
+### inline commands
+
+You can invoke up to three commands inlined within a message.  If the message
+is addressed to a nick, the output will also be addressed to them.
+
+    <pragma-> newuser13: Check the !{version} and the !{help} documentation.
+       <PBot> newuser13: PBot version 2696 2020-01-04
+       <PBot> newuser13: To learn all about me, see https://github.com/pragma-/pbot/tree/master/doc
+
+## Types of commands
+
+There are a few different types of commands in PBot.
+
+### Built-in commands
+
+#### Plugins
+
+### Factoids
+
+#### Code Factoids
+
+#### Modules
+
+## Command documentation
+
+### Administrative commands
+
+### Channel management commands
+
+### Miscellaneous commands
+
+