Association with message type code
Descriptor codes are associated with message type codes, specified by a letter following the message serial number, as follows:
- Code
- Type Code
- 1
- W (wait)
- 2
- A (action) or D (decision)
- 3
- E (eventual action)
- 4 through 10
- I (information)
- 11
- E (critical eventual action)
- 12 and 13
- I (information)