This is part of Family API which allow to create dual-os version of program runs under OS/2 and DOS
Note: This is legacy API call. It is recommended to use 32-bit equivalent
| Category | Description | 
|---|---|
| 1 | Serial Device Control | 
| 2 | Reserved | 
| 3 | Screen/Video control | 
| 4 | Keyboard Control | 
| 5 | Printer Control | 
| 6 | Light Pen Control | 
| 7 | Mouse Control | 
| 8 | Logical Disk Control | 
| 9 | Physical Disk Control | 
| 10 | Character Device Monitor Control | 
| 11 | General Device Control |