PM is a Parallel batch job class and runs in parallel pool. D1 is a Parallel batch job class and runs in parallel development pool. DM is a Parallel batch job class and runs in parallel development pool. Default values are as follows. For serial jobs only, do you want your job to be checkpointed.
Valid values are u for explicit checkpointing by the user and s for system checkpointing.
The default action is to not checkpoint your job. The job class you want to submit your job to. If you do not specify a value for class you will be prompted to select a class from a list. The list you see depends on the number of processors you indicate with the -np switch. If the number of nodes requested is greater than one you are assumed to be submitting a parallel job and the possible class values are P1 and PM for the Parallel execution nodes and D1 and DM for the Development Parallel nodes.