SMP/E orders the processing of the set of SYSMODs being accepted to ensure proper processing of element selection and source/macro update merges.

The order in which the SYSMODs being accepted are processed is determined from the prerequisite (PRE) data supplied on the ++VER statements of the SYSMODs. SYSMODs named as prerequisites are processed before the SYSMODs that name them.

If no prerequisite order can be determined between SYSMODs, function SYSMODs are processed first, followed by service SYSMODs (PTFs, then APARs, then USERMODs).