If a PAR routine completes its task successfully, it will return with status SAI__OK. If it detects an error condition, PAR defines the following error codes.
| Symbolic name | Meaning |
| PAR__ACINV | Invalid access mode for the parameter |
| PAR__AMBIG | Ambiguous option list |
| PAR__ERROR | Some undefined error |
| PAR__NULL | Null parameter value |