http://msdn.microsoft.com/en-us/library/ms195645(office.12).aspx says:
Quote
Evaluates one of the two expressions depending on the value of state.
USERUI(state,defaultexpression,userexpression)
Remarks
If state is 0, the USERUI function evaluates the defaultexpression. If state is 1, it evaluates the userexpression.
Example
USERUI(1, if(Width>6in, 6in, Width), Width*0.75)
Evaluates the expression Width*.075 and returns the result.
Has anyone played with this function? It looks to me as it does the same as a regular IF. What is it intended for?