protocol

This very specific noun applies to clearly defined, formal procedures or set of behaviours as they apply to ceremonies and similar events.

Protocol applies to written, formal missives that document how things have been done, are currently done and will continue to be done.

The expectation is that protocol will be followed without diversions unless these diversions have been confirmed and consolidated in writing.

In the law, government and diplomatic contexts, the breaching of protocol is a serious offence.