Any idno element in persons or places that are marked with a @subtype of "deprecated" should be hidden in the HTML view. These will include things like the old CBSC browse links which we want to retain for data provenance reasons, but which no longer resolve.
Initial data updates for this are in srophe/syriaca-data#1266, ready to be merged. Maybe we want to wait to merge until the xslt change is ready?