handle

               The handle attribute allows a client application
               to assign a client-generated request identifier
               to a Lock action.  The handle is included to 
               facilitate error reporting.  If one of a set of
               Lock actions failed while processing a LockFeature
               request, a WFS may report the handle in an exception
               report to localize the error.  If a handle is not
               present then a WFS may employ some other means of 
               localizing the error (e.g. line number).