MOUSECURSOR_* Constant Group
The "Down" variant is the version of the cursor when the mouse cursor is pressed down and usually has "d" in the filename. The non-down is usually in the game files referred to as "up" or "u" in the filename.
Custom ones can be added from custom_00 to custom_99 (filename: gui_mp_custom00u/d to gui_mp_custom99u/d). There are only constant definitions for the first and last of that range.
This constants group was added in 1.80.8193.14 of NWN:EE.