Error codes are defined in the header file. These codes fall into general and specific groups. General error codes that are appropriate to many Grexxx functions include:

┌──────────────────────────────┬──────────────────────────────┐
│Error Code                    │Must be logged by:            │
├──────────────────────────────┼──────────────────────────────┤
│PMERR_COORDINATE_OVERFLOW     │Functions requiring matrix    │
│                              │computation                   │
├──────────────────────────────┼──────────────────────────────┤
│PMERR_INSUFFICIENT_MEMORY     │Functions resulting in memory │
│                              │allocation                    │
├──────────────────────────────┼──────────────────────────────┤
│PMERR_INV_HBITMAP             │Functions with hbm as an      │
│                              │explicit or implicit parameter│
├──────────────────────────────┼──────────────────────────────┤
│PMERR_INV_HRGN                │Functions with hrgn as an     │
│                              │explicit or implicit parameter│
├──────────────────────────────┼──────────────────────────────┤
│PMERR_INV_COORDINATE          │Functions with coordinate     │
│                              │parameters                    │
├──────────────────────────────┼──────────────────────────────┤
│PMERR_INV_IN_AREA             │Functions that are invalid    │
│                              │inside an open area bracket   │
├──────────────────────────────┼──────────────────────────────┤
│PMERR_BASE_ERROR              │Functions that directly or    │
│                              │indirectly issue DOS routines │
├──────────────────────────────┼──────────────────────────────┤
│PMERR_DEV_FUNC_NOT_INSTALLED  │Functions not supported by the│
│                              │presentation driver           │
└──────────────────────────────┴──────────────────────────────┘

Specific error codes listed in the descriptions of each Grexxxfunction are found in Mandatory and Simulated Graphics Engine Function Reference.

To set an error code and the error's severity, the presentation driver must call WinSetErrorInfo (see WinSetErrorInfo). All error codes are listed and explained in the Presentation Manager Programming Reference.