3.3.4.2 Receive Preamble
The receiver MUST read the Version Record, as described in section 3.1.4.3.
The receiver MUST read the Mode Record, as described in section 3.1.4.4.
The receiver MUST read the Via Record, as described in section 3.1.4.5.
The receiver MUST read the Encoding Record, as described in section 3.1.4.6.
If the mode is Simplex, the receiver MUST read the Preamble End record as described in section 3.1.4.9.
If the mode is Singleton Unsized, or Duplex, the receiver MUST perform these additional steps:
If an upgrade is required, read the Upgrade Request Record, as described in section 3.1.4.7.
Read the Preamble End Record, as described in section 3.1.4.9.
The receiver MUST set Receive Allowed to TRUE.
If the mode is Duplex, the receiver MUST set Send Allowed to TRUE.