This helpfile also contains the LUA manual and a copy of the PaneAPI.html that shows all commands that SciTE can accept.

LUA script files are located the .....\SciTE\Lua folder and several of them have been specially written for SciTE4AutoIt3.

There is also an PersonalTools.lua in the %LocalAppData%\AutoIt v3\SciTE directory available in which you can develop and store your own Lua functions.