Several other constants, which do not fit into the above categories of constants, are also important.
| Constant | Description | Value |
|---|---|---|
| MAX_HOOKS | The maximum number of hooks allowed into the pen driver. | 0x00000004 |
| PENREG_DEFAULT | Signifies that Pen Services is in the default state, handling pen packets from the digitizer. | 0x00000002 |
| PENREG_WILLHANDLEMOUSE | Signifies that Pen Services will handle mouse movements and pass the mouse movement information to the Windows User library. | 0x00000001 |
| PLAY_VERSION_10_DATA | Used with the pen playback functionality; set if the pen packet passed in has the format of a pen packet from Version 1.0 of Pen Services. | 0x00000000 |
| PLAY_VERSION_20_DATA | Used with the pen playback functionality; set if the pen packet passed in has the format of a pen packet from Version 2.0 of Pen Services. | 0x00000001 |