| A | Addressing error, relative address is out of range | |
| B | not a Binary character | |
| D | not a Decimal character | |
| H | not a Hexadecimal character | |
| I | Illegal instruction | |
| M | Multiple definition of label attempted | |
| P | Phase error, value of label differs in 1st and 2nd pass | |
| S | Syntax error | |
| U | Undefinded symbol | |
| X | Extended address error, address must be single byte |