branches is an authorised value category in the database, but is not visible in the 'Show category' dropdown list in Administration - Authorised Values. This is confusing if a librarian tries to create an authorised value category called 'branches' because it will fail, since it already exists. It should appear in the authorised value category dropdown, though perhaps should not be editable from that screen, since branches should be created under Administration - Libraries and groups. Problem in 16.11, presumably in later versions too but I can't test that.
There are 3 authorised value "special categories": branches, itemtypes, cn_source. They are used to link a MARC subfield to a branchcode, itemtype or classification source. They are not proper authorised values (in the sense of the authorised_values table), but are needed to restrict the input. We could add them to the category dropdown list and remove the ability to add value to them (display a friendly message instead to explain the situation).
Yep that would be perfect. That way it's clear they already exist, and also that authorised_values is not the place to change them. Something like "[category name] is listed here for information only. To change or add values for [category name] use [appropriate place].
I have just tried: If you try to create a AV category "branches", there is a warning box with "The authorized value category 'branches', 'itemtypes' and 'cn_source' are used internally by Koha and are not valid." That seems enough to me.
(In reply to Jonathan Druart from comment #3) > I have just tried: If you try to create a AV category "branches", there is a > warning box with "The authorized value category 'branches', 'itemtypes' and > 'cn_source' are used internally by Koha and are not valid." > > That seems enough to me. I agree, this seems like the message the bug report asks for. Setting to Resolved.