Int 2F Fn 1220 U - Dos 3.0+ Internal - Get Job File Table Entry [D]
AX = 1220h
BX = file handle
Return: CF set on error
AL = 6 (invalid file handle)
CF clear if successful
ES:DI -> JFT entry for file handle in current process
Notes: the byte pointed at by ES:DI contains the number of the SFT for the
file handle, or FFh if the handle is not open
supported by DR DOS 5.0+
See Also: AX=1216h,AX=1229h