https://koha-community.org/manual/21.11/en/html/acquisitions.html#edi-process In the EDIFACT part of the manual there are a lot of broken links showing with the syntax ref:... Example: EANs: Each library using EDIFACT needs to specify a buyer identifier know as a SAN or EAN. This will fill in the :ref:`Library EANs <library-eans-label>` setting.
Some kind soul has re-worked the EDI process chapter from the 22.05 manual version and fixed this.