Inside Provider callbacks, this is the Item ID associated with the request, where applicable. Inside the Requestor Exception callback, this holds either an error exception (when DOSContext.Flags&DOSCONTEXT_FLAG_ERROR_EXCEPTION != 0), or the provider exception Item ID. In the Requestor's Signal and Change callbacks, this is set to the event's or property's Item ID, respectively. Other requestor callbacks do not have this set (it is not remembered from the request). Requestors set this field when sending a request. |