| . | CancelRequest | 16 | fe |
| . | SSLRequest | 8 | fe |
| . | StartupMessage | 9+ | fe |
| 1 | ParseComplete | 4 | be |
| 2 | BindComplete | 4 | be |
| 3 | CloseComplete | 5 | be |
| A | NotificationResponse | 10+ | be |
| B | Bind | 14+ | fe |
| C | Close | 6+ | fe |
| C | CommandComplete | 5+ | be |
| D | DataRow | 6+ | be |
| D | Describe | 6+ | fe |
| E | ErrorResponse | 7+ | be |
| E | Execute | 9+ | fe |
| F | CopyFail | 5+ | fe |
| F | FunctionCall | 16+ | fe |
| G | CopyInResponse | 7+ | be |
| H | CopyOutResponse | 7+ | be |
| H | Flush | 4 | fe |
| I | EmptyQueryResponse | 4 | be |
| K | BackendKeyData | 12 | be |
| N | NoticeResponse | 7+ | be |
| P | Parse | 8+ | fe |
| Q | Query | 5+ | fe |
| R | AuthenticationCleartextPassword | 8 | be |
| R | AuthenticationGSS | 8 | be |
| R | AuthenticationGSSContinue | 8+ | be |
| R | AuthenticationKerberosV5 | 8 | be |
| R | AuthenticationMD5Password | 8 | be |
| R | AuthenticationOk | 8 | be |
| R | AuthenticationSCMCredentials | 8 | be |
| R | AuthenticationSSPI | 8 | be |
| S | ParameterStatus | 6+ | be |
| S | Sync | 4 | fe |
| T | RowDescription | 6+ | be |
| V | FunctionCallResponse | 8+ | be |
| W | CopyBothResponse | 7+ | be |
| X | Terminate | 4 | fe |
| Z | ReadyForQuery | 5 | be |
| c | CopyDone | 4 | fe/be |
| d | CopyData | 5+ | fe/be |
| n | NoData | 4 | be |
| p | PasswordMessage | 5+ | fe |
| s | PortalSuspended | 4 | be |
| t | ParameterDescription | 6+ | be |