What are all possible process step statuses exist in MWS (not to be confused with process status) ? In which document I can find these details ?

Are you behind this? Refer 10-3_Bpm_Process_Development_Help.pdf or WmMonitor guide.

Step status

Completed
Eligible
Running
Waiting
Interrupted
Failed or canceled

Thanks Mahesh. I got all the status details from Monitor_Built_In_Services_Reference guide. But these are generic statuses which applies to both, processes and process instance steps. But I am looking for statuses which applies particularly to process instance step.

Hmm, in that case I need to check more on this (as they are internals). Let me know if you find it.