INT 21 - DOS 3.0+ - CREATE NEW FILE

	AH = 5Bh
	CX = file attribute (see #01420 at AX=4301h)
	DS:DX -> ASCIZ filename
Return: CF clear if successful
	    AX = file handle opened for read/write in compatibility mode
	CF set on error
	    AX = error code (03h,04h,05h,50h) (see #01680)
Notes:	unlike AH=3Ch, this function will fail if the specified file exists
	  rather than truncating it; this permits its use in creating semaphore
	  files because it is an atomic "test and set" operation
	under the FlashTek X-32 DOS extender, the filename pointer is in DS:EDX
SeeAlso: AH=3Ch,AH=5Ah