I want to validate the approvers in "Assigned To" field, so that only the approvers present in "Assigned To" box can approve or reject the document, and other users can not,they will get unathorized access message. This I am planning to do in infopath form load rules. Could somebody please help me out how can I check this condition in form load rules? By the way I am using sharepoint 2013 out of the box approval workflow.