(a) Calls and messages in each precedence classification above shall have no precedence over others within the same classification, except where, within the same classification, they cannot be handled simultaneously. Then, they shall be handled in the order of their receipt.(b) Individuals whose requirements qualify them to use the precedence system share the responsibility for insuring its effectiveness. Users must familiarize themselves with the purposes to be served by the use of each precedence designator. It must be remembered that the entire system will operate successfully only if the use of the precedence designator is limited strictly to the intended purposes. Each user must consider whether each message or call requires any special precedence and exercise care not to specify a higher precedence than circumstances require.(c) For public correspondence message services, the domestic or international precedence designators shall be shown in full by the sender as the first word preceding the name of the addressee.(d) For public correspondence call services, the user should first attempt to complete the call in the normal manner. In the event the user is unable to complete the call and the type of communication falls within one of the precedence categories listed herein the call should be filed with an operator for completion and the user must specify the required precedence handling by stating that this is a Flash Emergency, Immediate Emergency, or Priority Emergency call, whichever the case may be.(e) Any apparent misuse of precedence indicators by non-Federal Government activities brought to the attention of the communication common carriers shall be referred to the FCC on and after-the-fact basis.(f) Any apparent misuse by Federal Government activities brought to the attention of the communication common carriers shall be referred to the Executive Agent, National Communications System. The Executive Agent will refer any matter which cannot be resolved with the cognizant Government activity to the National Security Council, for decision.(g) It is essential to provide public message and call capability for the transmission of military, governmental, and essential non-Government precedence messages and calls. Private line services for military, governmental, and other essential users are protected under a Priority System for Intercity Private Line Services promulgated by the FCC (FCC Order 67-51) and the National Security Council. However, during national emergencies, military, governmental, and other essential users will have additional requirements for prompt completion of precedence traffic over public correspondence communication common carrier facilities. Therefore, notwithstanding the provisions of the above-described Priority System for Intercity Private Line Services, communication common carriers shall have available a minimum number of public correspondence circuits at all times so as to provide for the transmission of precedence type messages and calls. Normally, the communication common carriers shall use their judgment in determining this number of circuits required for public correspondence precedence traffic. However, the authority is reserved to the National Security Council or the Federal Communications Commission, as appropriate to the time and situation, to revise the decisions of the carriers respecting the allocation of circuits, and to resolve any questions which are referred to them by the carriers or the users.