RBIL61 - INT 2F - NETWORK REDIRECTOR (DOS 4.0+) - "UPDATE_CB" - ??? {callout or callback, undocumented}

INT 2F CU - NETWORK REDIRECTOR (DOS 4.0+) - "UPDATE_CB" - ???
	AX = 112Ch
	SS = DOS DS
	SDAsee Swappable Data Area current SFTsee System File Table pointer -> SFTsee System File Table for file
	???
Return: CF set on error
Note:	called by SHARE in DOS 5.0-6.0