INT 2F CU - MS Windows WINOLDAP - SWITCHING ???                                 
	AX = 4601h
Return: ???
Note:	the DOS 5+ kernel intercepts this function and copies the MCBsee Memory Control Block
	   following the caller's PSPsee Program Segment Prefix memory block into the DOS data segment;
	   in conjunction with AX=4602h, this intercept is used by DOS to
	   avoid corruption of the Windows real-mode heap's end sentinel
SeeAlso: AX=1700h,AX=4602h