Multilevel precedence and preemption

Multilevel precedence and preemption (MLPP): In military communications, a priority scheme (a) for assigning one of several precedence[?] levels to specific calls or messages so that the system handles them in a predetermined order and time frame, (b) for gaining controlled access[?] to network resources in which calls and messages can be preempted only by higher priority calls and messages, (c) that is recognized only within a predefined domain, and (d) in which the precedence level of a call outside the predefined domain is usually not recognized.

Source: from Federal Standard 1037C