There are other Macro programs being called from within O9001 and O9002. For example O100 is being called by the N20 block where you state a P/S 78 alarm is being raised. This alarm is raised when a program number or a sequence number which was specified by address P in the block which includes an M98, M99, M65 or G66 was not found. Accordingly, with regards to block N20, O100 doesn't exist in the control's memory.
Other programs that need to be loaded into memory are:
O15, O40, O125, O850, and whatever number is represented by common variable #500