RBIL61 - INT 2F - DOS 3.0+ internal - DECREMENT SFT REFERENCE COUNT {undocumented}

INT 2F U - DOS 3.0+ internal - DECREMENT SFTsee System File Table REFERENCE COUNT
	AX = 1208h
	ES:DI -> SFTsee System File Table
Return: AX = original value of reference count
Notes:	if the reference count was 1, it is set to FFFFh ("busy", since 0
	  indicates that the SFTsee System File Table is not in use).  It is the caller's
	  responsibility to set the reference count to zero after cleaning up.
	used by network redirectors such as MSCDEX
SeeAlso: AX=1106h