From:	MERC::"uunet!CRVAX.SRI.COM!RELAY-INFO-VAX" 26-JUN-1992 12:43:41.38
To:	INFO-VAX <INFO-VAX@KL.SRI.com>
CC:	
Subj:	RE: vms backup operating system

Hi,

>
>	In VMS BACKUP format, there is an "opsys" data type which appears to
>	indicate which operating system was running BACKUP.  VAX/VMS is
>	apparently code 1024.  Does anyone out there know if any other codes
>	have been used or reserved?
>
>RSTS uses the same BACKUP format, so presumably has a defined value.  That's
>the only other DEC BACKUP implementation I know of, and if there is any
>reservation procedure, it's going to be purely internal to DEC.
>
>A search of the BACKUP.EXE image reveals that the "Operating system:" string
>that you see on BACKUP/LIST has the name "VAX/VMS" hard-coded in.  The string
>"RSTS" doesn't occur anywhere.  So it seems that VMS BACKUP doesn't really
>even recognize the existence of RSTS BACKUP!
>
>One place where standardized OS id numbers occur is in DECnet - somewhere in
>link setup, I forget exactly where, the OS's identify themselves to each
>other.  I have no idea if VMS uses 1024 in this context; if so, the other
>id's used there are natural things to use.
>							-- Jerry

the "magic" value 1024 is actually BACKUP$K_OPSYS. This value is internal to
the various BACKUP implementations. The DAP code, which Jerry is refering to
uses totally different numbers: DAP$K_RSTS = 2, ... DAP$K_VAXVMS = 7. Use BACKUP
/LIST/ANALYZE to look at your save sets if this sort of detail bothers you.

regards,

nick	DESMITH_N@COLLOQUIUM.CO.UK
	NICK@NCDLAB.ULCC.AC.UK