| RFC | Status | Reference | Notes |
|---|---|---|---|
| 435 | Status Unknown | B. Cosell; D. Walden (5 January 1973). TELNET Issues. Network Working Group. doi:10.17487/RFC0435. RFC 435. | NIC 13675. |
| 439 | Status Unknown | V. Cerf (21 January 1973). PARRY Encounters the DOCTOR. Network Working Group. doi:10.17487/RFC0439. RFC 439. | NIC 13771. |
| 495 | Status Unknown | A. McKenzie (1 May 1973). TELNET Protocol Specification. Network Working Group. doi:10.17487/RFC0495. RFC 495. | NIC 15371. Updated by RFC 562. |
