Community Question - What Built In Variables Would You Add?

[Larkal]

If you had your choice to add built-in variables to the main branch of AHK2 what would you add and why?

For me, I would personally add A_AhkDir (AutoHotkey_H ftw), A_AppDataLocal, A_ProgramData (looking at you A_AppDataCommon).

A_AhkDir, because I use it often enough.
A_AppDataLocal, so I don't have to do A_AppData "\..\Local\"
A_ProgramData, I like the idea of the folder name matching the variable name.