Text to go in the release notes:
This enhancement allows patrons to cancel holds waiting for pickup from their account (summary > holds > request cancellation button), instead of having to contact the library (for example, by email, phone, or in person).
This is enabled by setting rules by library, patron type, and item type. The rules are set from a new "Default waiting hold cancellation policy" section under Administration > Patrons and circulation > Circulation and fines rules.
Cancellation requests are listed in a new tab "Holds with cancellation requests" under Circulation > Holds > Holds awaiting pickup.