Nick,
You should try something like this
*XDIM_MEMBERSET AUDIT_ID = INPUT
*XDIM_MEMBERSET ACCOUNT = BAS(NET_PROFIT)
*WHEN ACCOUNT
*IS *
*REC(EXPRESSION= ((%VALUE%>0)*1), AUDIT_ID = PROFIT_SHARE) // Write value to Profit Share Audit ID
*ENDWHEN
Please also check out page 25 in this document
Good luck!
Akos