Ok this maybe sounds noobish but i read it in many spell request threads and i yust cant figure what it is so where does it stand for and what is it actualy?
Some things that are useful to know is for example:
1) There is also MPI (Multi Player Instancable; One unit of each player can cast the same spell at the same time without variable-overwritings) which is easier than MUI to achieve in GUI.
2) Triggers with no waits are MUI, assuming they do not use any dynamic triggers in the code themselves.
3) Using (Triggering Unit) is fully MUI with waits.
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.