Each work Item will be assigned two ID's, Job Id and Activity Id. When any work Item is created, a Workpoint is assigning job Id as well as activity id. Job Id will be same through out the approval process like 1234:WPDS. IDM is not appending 1 into WP ID. Workpoint is appending 1 and it is incremental when one process has sub-process.
Similarly Workpoint is appending 0 into activity Id which is incremental, representing how many iteration done between Approver and requester if any changes request done by approver (Consultant Process is one of the example).
If requester needs to change it, the ID will increment by one. If a value has to be changed it sends back to requester and the value will be changed and increment will go up by 1. Otherwise, it will always be 1. "1 1234:WPDS" is workpoint process definition id generated by IDM where 1234 is the job ID(generated by Workpoint) and 1 is pre-pending by IDM to job ID. Each job has one or more activity and each activity has its own id like 1 4 1621:WPDS is a work item id generated by IDM where 1621 is activity id(generated by Workpoint), 4 is pre-pending to 1621 by IDM and 1 is iteration (it is incremental and generated by workpoint).
Here are all the different valid codes:
WF_OBJECT_TYPE_PROCESS_INST = 1;
WF_OBJECT_TYPE_ACTIVITY = 2;
WF_OBJECT_TYPE_ACTIVITY_INST = 3;
WF_OBJECT_TYPE_WORK_ITEM = 4;
In this file you will see how the Job ID can change from 1,2,3, or 4. The same is true for the second number which is the workitem activity. Those are all the possible incremental values 1,2,3, or 4 for the Job ID and workitem activity.