Does anybody know how to have tip text shown for each parameter of
user-defined worksheet functions? For instance, I have the following function
in a module:

Public Function KAK(Ind As Double, Lb As Double, Ub As Double, _
Avr As Double) As Variant
If Avr = 1 Then
KAK = (Log(Ub - Lb) - Log(Ub - Ind)) / Log(Ub - Lb)
ElseIf Avr 0 And Avr < 1 Then
KAK = ((Ub - Lb) ^ (1 - Avr) - (Ub - Ind) ^ (1 - Avr)) _
/ ((Ub - Lb) ^ (1 - Avr))
End If
End Function

I want to display tip texts, so that when the user types "=KAK(" in a cell,
the tip text would display "Indicator" in bold, reminding her of what
parameter is required first, then after the first comma is entered "Lower
bound" would be shown or turn bold, then "Upper bound" and so on.

Thanks in advance for your help!

Rafael