I beilieve you mean custom script and if you do read on
1.They allow gui to do things it usually couldnt do(especially getting rid of leaks)by putting some jass into it.
2.you make one by using the action, then using custom script in the trigger menu.
3.When you look at the trigger part of it will be gui while some will be jass which is the custom script part.
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.