Master Floor Index

The Master Floor Index is the principal registry of floor designations, names, and numerical assignments maintained for the whole of the Tower, held on The Index and administered jointly with the Master Index. Unlike the Master Index, which catalogues subjects and holds abstracts of catalogued items, the Master Floor Index records only the floors themselves: which numbers are in use, which names attach to them, and which numbers have been retired, quarantined, or returned to circulation. It is the oldest continuously amended document in the archive. No complete recension survives, and by the admission of its own keepers it has never been read in full by any single person.

Scope and method

The Index does not describe what is on a floor. That is the work of the floor's own catalogue and, ultimately, of the Master Index. The Master Floor Index answers a narrower question: whether a floor may be said to exist in the numbered sense. A newly discovered floor is entered provisionally, assigned a number drawn from the Fixed Ladder Index, and marked with a kappa-temporary designation until survey is complete.

Full integration into the Master Floor Index requires a subsequent review after a kappa-temporary designation, a rule introduced following the Kappa Incident of 9 Rain, 388, in which fourteen provisional floors were integrated and then found to be the same floor surveyed fourteen times from different stairheads. The consolidated entry now carries a note in the margin, in the hand of the surveyor, Clerk Amarin Vess, reading: "Once, and let it be once."

Certain entries are reserved rather than assigned. The numbers held in reserve are not published in the ordinary recension but are recorded in the Master Index of Non-Sequential Gaps, which functions as the Index's annex of absences.

Relation to the Master Index

A floor is not considered fully instantiated until its catalog is ratified and integrated into the Master Index. The two documents are therefore bound together by a procedural knot: the Master Floor Index cannot close an entry until the floor's catalogue is ratified, and the Master Index will not ratify a catalogue submitted under a floor number the Master Floor Index has not closed. The standing resolution, renewed at each Diurnal Concordance, is that ratification proceeds on the floor's provisional number and the closing happens afterward.

"Where the two registers disagree as to whether a floor exists, the floor exists. Where they disagree as to what it is called, the older hand prevails."

— Third Concordance, Annex 4, clause 7

The clause has been cited in every boundary dispute since its promulgation and satisfies neither register. The Fourth Concordance, Annex 1, clause 2, appears to reverse it, though the reversal is printed in a font used elsewhere in the Fourth only for examples, and the Master Index (person) has declined to rule on which reading governs.

Landmark entries

Floor 45 is where the administrative Master Index is located, and its entry in the Master Floor Index runs to nine folios, mostly amendments concerning the corridor. Floor 33-Δ of the Central Index houses the master scroll of the Central Index, and its designation is the only one in the Index written with a Greek letter; the entry includes a note that the letter is to be struck only on the authority of the Librarians, which has not been given. Floor 0 is entered first and last, an arrangement retained from the earliest recension and defended on the grounds that the Index must begin and end somewhere it can be checked.

The entrance for the Sub-Index of Unfulfilled Prophecies was for sixty years listed under a number that had already been assigned to a stairwell. Both entries remain, cross-referenced, and neither has been corrected.

Scholarly dispute: the completion date

The Master Floor Index records the completion date of The Deterministic Codex as 17 Rain, 412. This is the Index's single most contested entry. The Codex's own colophon gives 17 Rain, 411, and the Grand Taxonomy cites the earlier year without comment. The Master Folio of the period records no entry at all.

The dispute turned bitter in the winter of 412, when Index-Tender Miro Savel produced a folio showing that the Codex had been completed twice — once in draft, once fair — and that the Index, by long usage, dates completion from the fair copy. Savel's folio was accepted by the Master Floor Index and rejected by the office of the Master Index Object, which maintains that an object cannot be completed twice. Savel was subsequently reassigned to the reconciliation of the Index of Unspoken Prefaces and did not return to the question. The entry stands as written.

Access and custody

Custody of the Index rests with the Master Index (person), who delegates its daily keeping to the floor clerks. Consultation is by appointment made at the desk on Floor 0, in person, and not more than three days ahead. Readers may not copy entries concerning floors they have not visited. The prohibition is old and its purpose is not recorded; the clerks enforce it without explanation, and visitors who object are shown the margin of the Kappa Incident and generally stop objecting.

Copies of each amendment are sent to the Satellite Index of the floor concerned and to the Master Index of Resolved Contradictions where an amendment resolves one. The Index of Intentionality is not integrated into the Master Index and, by extension, is not consulted in the amendment of the Master Floor Index, a point raised annually and annually deferred.