The list of available search fields is limited... why ?

I would really like to search for a specific workflowstep without having to set up a filter.  Can you tell me why some fields (such as workflow step, assigned to etc.) are not available... or is it my issue as in a setup problem ?  I note that an Ontime response to an earlier post (Filtering / search in Customer Portal ) suggested that workflow step search would be added to desired Ontime Features list. I don;t see it there - though that was back in April. I am also not sure that this is the same issue .. I am not using customer portal.  Awaiting comment please. ... Thanks ... Lynn