3.2.4.5 Message Processing Events and Sequencing Rules

The messages and PDUs listed in this section correspond to events in the state diagram in section 3.2.4.

All messages not specifically listed in this section and not marked for PDU forwarding as specified in section 3.2.1.5.2, or messages whose syntax is specified in section 2 of this protocol as invalid, SHOULD be treated by implementations of this protocol on the outbound proxy as protocol errors as specified in section 3.2.4.5.14.