Limiting the Values in a List Box - OR - in a Pivot Table Dimension

[#1]

For logical application flow I need to be able to limit items returned from a field into a List Box.

I have a field called ProductGroup with roughly 10 values. For some of my document sheets I only want to analyze a few at a time, so I want to limit the values in the List Box.

I have used IF in some cases (Example: IF(ProductGroup='A' or Product='B', ProductGroup), but this seems to lead to misleading results when no value is selected. In the case that nothing is selected in the List Box, the user is left to assume that the data reflects only 'A' and 'B', when in reality it is all ProductGroups, not just th filterd list of 'A' and 'B'.

Is there another away to filter to a subset of the values in a field?

[boorgura]

you can place a condition on the expression, saying:

if(getSelectedCount(ProductGroup) = 0, <place a condition for product group A & B>, <regular expression>)

Thanks,

Rocky

[#3]

were in the List Box object do you put the formula to limit the list values

[#4]

I placed mine in the Expression listed way at the bottom of the list of fields on the List Box.  Hope it helps!