Registration
The single text behind this umbrella is Isaiah's vision of a purified remnant whose names are kept on a written roll in Jerusalem.
Of Citizens
The promise looks past judgment to the survivors of Zion: "And it will come to pass, that he who is left in Zion, and he who remains in Jerusalem, will be called holy, even everyone who is written to life in Jerusalem" (Isa 4:3). Belonging to the holy remnant is registered — those left and those remaining are "written to life" in the city.