Bitfields for parsing options:
Bit(s)	Description	)
 0	skip leading separators
 1	use existing drive number in FCB if no drive is specified, instead of
	  setting field to zero
 2	use existing filename in FCB if no base name is specified, instead of
	  filling field with blanks
 3	use existing extension in FCB if no extension is specified, instead of
	  filling field with blanks
 4-7	reserved (0)