⚑ Carried in Part X because no register of cultural institutions exists yet, and not written: a museum is not an authored house of hospitality, and writing these would fix to the Library a subject that is not its own. Listed so that every code has an address (§6.1).
Each row says what is behind its code before you follow it. Article — the entry is written and has its own page. Brief — no page of its own yet; the link leads to whatever holds it. Register row — the code exists and the entry is not written. Withdrawn — the code was retired and the line says where the subject went, which may be another of our series or a partner register. The register is wider than the library of written entries, and always will be; this line is here so the interface does not pass one off as the other.