[Info-vax] Question about checksum in BACKUP block headers

[Anton Lavrentiev]

Thank you so much, Volker!

So the checksum is indeed a regular CRC-16 (0x8005), which is what I suspected
(as it changes dramatically even with minor data variations in the header).
The mistake I was making was assuming that it summed only the preceding 127 words,
that is, not including itself.  Turns out, it does include the last word (itself)
set to zero.  Also, thanks to your code I see that the data block CRC must also be
reset to 0 when verifying the header checksum, which is kinda weird, TBH, but I'm
sure there was a reason to implement it like that :-)

Now my BACKUPs verify correctly!

Cheers,
Anton