scmJS docs

MBRF

The mission briefings, in the same 2400-byte record as a trigger, with their own set of actions.

Name MBRF (4D 42 52 46)
Size 2400 bytes per briefing.
Read by The game.
Required Yes. The game does not load a map without it.
More than one copy Every copy counts: the records of all of them, in file order.
In scmJS Read, and written again when you change what it holds.

Each briefing:

Offset Type Holds
0 u8 × 2400 One briefing, in the same record as a trigger