INT 2F U - DOS 3.0+ internal - CLOSE CURRENT FILE                               
	AX = 1201h
	SS = DOS DS = DOS kernel data seg (must be using a DOS internal stack)
	SDAsee Swappable Data Area current SFTsee System File Table pointer -> SFTsee System File Table of file to close
Return: CF set on error
	ES:DI -> SFTsee System File Table for file
	CX undefined (new reference count of SFTsee System File Table in many versions)
	BX destroyed
SeeAlso: AX=1106h,AX=1227h,INT 21/AH=3Eh