Category: <b>DOS kernel</b>
<p>
<pre><b>INT 21 - DOS 2.x and 3.3+ only - "AVAILDEV" - SPECIFY \DEV\ PREFIX USE</b>

	AH = 37h
	AL = subfunction
	    02h get availdev flag
		Return: DL = 00h \DEV\ must precede character device names
			   = nonzero \DEV\ is optional
	    03h set availdev flag
		DL = new state
		    00h		\DEV\ is mandatory
		    nonzero	\DEV\ is optional
Return: AL = status
	    00h successful
	    FFh unsupported subfunction
Notes:	all versions of DOS from 2.00 allow \DEV\ to be prepended to device
	  names without generating an error even if the directory \DEV does
	  not actually exist (other paths generate an error if they do not
	  exist); DOS 2.x has an AVAILDEV= option in CONFIG.SYS to make \DEV
	  mandatory
	although MS-DOS 3.3+, DR DOS 3.41+, and Novell DOS 7 accept these
	  calls, they have no effect, and AL=02h always returns DL=FFh (except
	  for Novell DOS 7, which leaves AX unchanged for both subfunctions)
</pre>