Yep, forgot that --

But, just do a wrapper with a different name around MAX and that should work:

FUNCTION MAX4Select
PARAMETER    x1, x2, x3, x4
RETURN MAX (x1, x2, x3, x4)

It's probably easier, in a scenario like this, to hardcode the interface -- this accepts 4 and only 4 parameters -- to avoid problems of data type mismatch if actual parameters don't match formal parameters.

Jay