>That is, I had to delete the trailing 978 (for "Bookland") and edit the
>last ("control") digit, from the 13-digits string usually produced by a
>barcode scanner.


A lot of times, that digit has nothing to do with the actual ISBN.



>E.g., 9780486650159 should be edited to 0486650154.
> ^^^ ^ ^^^ ^
>
>I think this is a bit unconvenient. Since I am a newbie to Koha, I wonder
>whether this is a feature or a bug: which way should one enter one's
>ISBNs, with or without the trailing 978?
>

Currently, that 978 is not part of the NISO standards. In a few years, it will be. See:

http://www.niso.org/standards/resources/ISBN.html

Cheers,
Brooke @ Hinsdale MA