INT 6E - DECnet DOS - DECnet NETWORK PROCESS API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running.  Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes.
InstallCheck:	test for the signature/data area (see #03737) immediately prior
	  to the interrupt handler
Note:	this is the main DECnet DOS access, and is described in Digital manual
	  AA-EB46B-TV ("DECnet-DOS Programmer's Reference Manual")
Index:	installation check;DECnet DOS

Format of DECnet DOS signature area:
Offset	Size	Description	(Table 03737)
 -5	BYTE	major version number
 -4	BYTE	minor version number
 -3   3 BYTEs	signature (ASCII "DNP")