The Umbral Accord is the agreement among great powers of the galaxy concerning the Umbral Ring and shared standards for the lanes. It is named for Umbra, the black hole at the galactic heart. Umbral is the adjectival form used in Umbral Ring and Umbral Accord. Do not call the hole Umbral.
This instrument is a treaty. It is not an empire. It does not issue citizenship, raise a single legion, or claim one capital as its own. Signatories remain sovereign in their own houses. Local life (capitals, Axioms, Senates, Psion orders, arrival stations) belongs to the governments and civilizations under this Accord.