Table 1 VxD Control Messages

Sys_Critical_Init   The first control event; interrupts disabled. VxD
                    determines device availability.
Device_Init         Interrupts enabled; VxD initializes device; may call
                    DOS routines and drivers.
Init_Complete       Indicates that all VxDs have been through
                    Device_Init.
System_Exit         Indicates that Windows is preparing to shut down and return to
                    DOS.DOS memory has been restored to pre-Windows
                    state.
Sys_Critical_Exit   The last control event; interrupts disabled.
Create_VM           Called when a VM is about to be created; VxD
                    indicates if resources are available to allow VM
                    creation.
VM_Critical_Init    Second phase of VM creation.
VM_Init             Third phase of VM creation. VxD may abort the VM
Sys_VM_Init
Query_Destroy       Allows VxD to warn user of problem with destroying a
                    VM.
VM_Terminate        First phase of normal VM termination. When the
                    system
Sys_VM_Terminate    VM, indicates user-directed (normal) shutdown of
                    Windows.
VM_Not_Executeable  VM is shutting down. First phase of abnormal VM
[sic]               termination.