APO DP macro to test posting period

I am using APO DP v5.

In DP, I am using periods defined as posting periods, for example period number 001 of yeay 2007.

I need to check the posting period in DP macros. Which standard macro function could I use to test the value of the period, specifically the period number within the year and the year?

Thanks,

Bob Austin, Atos Origin