Session-switching and saving/restoring notifications are not given when switching between non-full screen sessions (that is, between Presentation Manager sessions and text-windowed sessions). Termination and creation notifications are given in all cases.

For requests with an Action parameter value in the range of 1-64, refer to the DosStartSession API in the OS/2 Control Program Programming Reference for Session ID/Type parameter values and descriptions. Any request received by a physical device driver that does not match the Length/Action parameter values, as defined above, is returned to the caller with an ERROR_INVALID_PARAMETER error code.