A long standing bug needs ideas from the koha community, bug 906 [1]. Pascale raised the idea of including some kind of validation to the ISBN field (be it 10$a in UNIMARC or 20$a in MARC and NORMARC). Both cataloguing standards reserve the $z for saving an invalid ISBN. I've written a JavaScript checker that, hooked into the "Save" action, prints an error message provided a syspref is set to enable ISB validation (the same message dialog is used for missing mandatory fields). The patch is attached to the bug and is fully functional. The main concern of the QA team about it is that the approach is not modular enough, and it might be better tackled using plugins. It sounds perfect to me, but I'm not sure how plugins work. I might start reading that code (i will anyway) but as some of you have more experience in this kind of sutff I ask: What is the desired workflow actually (in the case of invalid ISBN)? and, does the (current) plugin implementation fit for it (perhaps using an AJAX call)? Regards To+ [1] http://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=906