Volumes organise; they never renumber. An entry keeps its code wherever it is filed (§6.1).
Every volume has its own page. The full list of entries lives there rather than here: a hub that repeats every row is a second register to keep in step, and the register already exists.
No entry in this Part carries a page yet: each holds a code and a row and nothing more. That is the honest state of the Part, and a code without an article is still a permanent address — this page answers to it. Counts and order are read from register v60.25 at build time; they are not maintained here.