https://koha-community.org/manual/17.11/en/html/02_administration.html?highlight=checkprevcheckout#checkprevcheckout CheckPrevCheckout is described as a simple on/off setting. But reading the commit message shows there is more to it: - Per patron category pref allows libraries to create overrides per category, falling back on the global setting by default. - Per patron pref allows switching the functionality on at the level of patron. Fall-back to category settings by default. https://bugs.koha-community.org/bugzilla3/attachment.cgi?id=53144 As far as I can tell, the per patron category and per patron prefs/settings appear based on what CheckPrevCheckout is set to.
I just sent in a merge request to the manual for this. https://gitlab.com/koha-community/koha-manual/merge_requests/186