I've been approached by one of our librarians asking for a way to validate ISBNs inside koha. I've found http://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=906 but I need more infomration on: 1) The fields that need to be validated (MARC21 -> 020$a?, UNIMARC -> 010$a?) 2) The expected behaviour we want for this validation (I know 020$z can be used for "invalid" or "canceled" ISBN, but aint no expert on the subject): abort? warning? option to move ISBN to $z?. I'm not sure also how is this related to the use of EAN instead of ISBN by several publishers and if it has to be checked too (are they mutually exclusive?). I didn't have time today to read the references on this, and hence my question Have a nice weekend. To+