Dave those are ANSI tape labels.  Unix does not use them    DEC did although was inconsistent with the use particularly WRT HDR2 records.  Tom Quarles (of spice 3 fame) wrote probably the best version for Unix to deal with them.  I believe I gave a copy but it will be in BSD 4.1 maybe 4.2 compiler syntax. I'll ask him if he ever updated it. Clem

On Sat, Aug 1, 2020 at 3:55 AM Dave Horsfall <dave@horsfall.org> wrote:
On Sat, 25 Jul 2020, Warner Losh wrote:

>       Weren't V5/6/7/etc distributed as bootable tapes?  Set the switch
>       register to point to the tape instead of the disk...
> Yes. They were. We have V6 and V7 tapes (and a V5 disk image). Likely
> earlier versions likely did too.  What I'd meant was that 2.8BSD is the
> first 2BSD that had a bootable tape.

Ah, my mistake.

I think the loader also read just the first block, so woe betide you if
you used a labelled tape...

If I recall, VOL1, HDR1, etc.

-- Dave
Sent from a handheld expect more typos than usual