| 0x0D | Internally generated for SNALink lost locality. |
| 0x11 | DSR failure. |
| 0x12 | CTS failure. |
| 0x14 | DCD failure. |
| 0x24 | Nonproductive receive retry limit exceeded. |
| 0x25 | Idle time-out retry limit exceeded. |
| 0x29 | Connection problem. subqual = 0x00 I-frame retransmission subqual nonzero XID retransmission |
| 0x2D | Abnormal modem response. |
| 0x2E | Write time-out retry exceeded. |
| 0xA0 | XID exchange failed on multidrop line. subqual is address of secondary station. |
| 0x15 | DISC received. |
| 0x23 | Receive buffer overrun. |
| 0x2C | Invalid command received. subqual = 0x03 invalid N(R) subqual = 0x04 invalid or unsupported command/response subqual = 0x05 excess I-field |
| 0x80 | DM received in information transfer state. |
| 0x81 | Discontact retry limit exceeded. |
| 0x82 | Contact retry limit exceeded. |
| 0x83 | Poll retry limit exceeded. |
| 0x84 | No Response retry limit exceeded. |
| 0x85 | Remote busy retry limit exceeded. |
| 0x86 | FRMR received. subqual = 0x00 no reason given subqual = 0x03 invalid N(R) subqual = 0x04 invalid or unsupported command/response subqual = 0x05 excess I-field |
| 0x87 | Invalid frame received. subqual = 0x03 invalid N(R) subqual = 0x04 invalid or unsupported command/response subqual = 0x05 excess I-field |
| 0x88 | RIM received. |
| 0x89 | RD received. |