In PM Order, PM02 will be used to differentiate the process flow. PM Order - PR - PO - GR.
Now SAP has given the option of doing Subcontracting Process by tracking the goods movements as well.
You need to activate LOG_EAM_ROTSUB and / or LOG_EAM_ROTSUB_2 for this. So that, for PM02 control key, Subcontracting tick mark will be enabled in PM order.
You can refer the above links to understand the process well.