When a subtask is created, the limit and dispatching priorities of the subtask are the same as the current limit and dispatching priorities of the originating task except when the subtask priorities are modified by the LPMOD and DPMOD parameters of the ATTACH and ATTACHX macro. The LPMOD parameter specifies the signed number to be subtracted from the current limit priority of the originating task. The result of the subtraction is assigned as the limit priority of the subtask. If the result is zero or negative, zero is assigned as the limit priority. The DPMOD parameter specifies the signed number to be added to the current dispatching priority of the originating task. The result of the addition is assigned as the dispatching priority of the subtask, unless the number is greater than the limit priority or less than zero. In that case, the limit priority or 0, respectively, is used as the dispatching priority.