End of list - multiple selections on a list how to determine last results.

Here is what I would like to do if it is possible within Crystal reports 9. I have a list of 9 product numbers and I am creating a AS400 macro within the Crystal Report so I need is a way to determine that I used the last product number in the list so I can end the macro. The list can vary based upon what product I am using so the 9 is not a constant.
Example:
Product # 101, 205, 206, 308, 400 (these numbers are reuslt of the report selection criteria). I have the macro in the report design and reference this Product# field for one of the macro steps and repeat that line once for each entry but I need to know when I use 400 so I can then end the macro for the AS400. Is there anything within Crystal report 9 that identfies the last entry in a listing?

I am a novice user with a little information (which can be dangerous) but I would appreciate any help if there is anything that can be done.