)
Call VLM CallA entry point with:
	AX = function
	    0000h submit
	    0001h cancel (not implemented)
	ES:DI -> Overlay Asynchronous Control Block structure (see #02894)
Return: DI, DS, ES preserved; all other registers may be destroyed
	interrupts disabled
Desc:	asychronously call the specified VLM and then return to caller, which
	  might be another VLM