The Bureau of Aperture Consistency

The Bureau of Aperture Consistency is an office situated within Spiral 9, charged with ensuring that designations applied to apertures are applied uniformly across all linked spirals. It is distinct from the Bureau of Geometric Consistency, which measures apertures, and from the Bureau of Aperture Traffic, which schedules their use; the Bureau of Aperture Consistency neither measures nor schedules, but confirms that a given aperture is called the same thing in every spiral where it appears, and that the same designation has not been quietly attached to two apertures at once. Its founding instrument, the Eleventh Concordance, Annex 6, describes the office's purpose in a single sentence: "That a name, once affixed to an opening, shall not drift."

The Bureau occupies four rooms on the ninth landing of Spiral 9, one of which is given over entirely to the storage of designation plates. It maintains no field staff. All of its work is done from returns.

Origin and the Plate Question

The Bureau was constituted in the winter of the year recorded as 3,412 by the internal reckoning of Spiral 9, following an incident on the seventh gallery in which three separate apertures were found bearing the plate Aperture 14. The plates had been issued by three different scriptoria over the course of some forty years, each acting on a return that had described a different opening. The incident is recorded in the Bureau's opening ledger as the Plate Question, and it is the only entry in that ledger written in a different hand from the rest — a clerk named Ondrej Vasp, who had been sent to catalogue the seventh gallery and instead spent eleven days counting plates.

Vasp's report recommended, and the Bureau of Spatial Designations subsequently adopted, the rule that a designation may be affixed to an aperture only once, and that the affixing be recorded in the spiral of first appearance rather than the spiral of most frequent use. The rule has been amended four times. Vasp left the Bureau shortly afterwards and is not recorded as having commented on any of the amendments.

Relationship to Aperture Gamma

The greater part of the Bureau's casework concerns Aperture Gamma systems, the vertical access points and interstitial spaces that exhibit non-Euclidean topological consistency. Because a Gamma aperture may present different apparent widths, and in some recorded cases different apparent positions, depending on the spiral from which it is approached, the question of what is to be designated is not straightforward. The Bureau's standing position, set out in its Fourth Procedural Memorandum, is that the designation attaches to the aperture and not to any of its appearances. An aperture that looks like two apertures from the fourth spiral is still one aperture and bears one name.

This position has been contested by the Office of Spatial Integrity, which argued in a submission of the year 3,449 that where an aperture presents in two places it should be designated twice and the two designations cross-referenced through the Bureau of Referential Integrity. The Bureau of Aperture Consistency rejected the submission on the grounds that it would require the Master Cross-Reference Ledger to expand at a rate the Ledger's custodians had already described as unsustainable. The rejection is recorded without further comment.

The Dispute with the Bureau of Geometric Consistency

A long-running disagreement obtains between the Bureau of Aperture Consistency and the Bureau of Geometric Consistency over the point at which an aperture ceases to be one aperture. The Geometric Bureau's biannual surveys, conducted with Attenuation Lenses under the authority of the same Bureau's measurement mandate, report deviations exceeding 0.0033 cubits per linear perimeter; where such a deviation is found in an aperture that has been designated, the Geometric Bureau has on eleven occasions recommended that the designation be retired and a new one issued. The Consistency Bureau has refused all eleven, holding that a deviation in the boundary of an aperture is not a deviation in the aperture.

"The boundary may move. The opening does not become another opening by moving. A door that has been widened is the same door, and to call it otherwise would require us to rename every door in the Tower each time a hinge is replaced."

— Bureau of Aperture Consistency, Fourth Procedural Memorandum, clause 12

The Geometric Bureau's answer, filed under protest in the same year, is that clause 12 conflates the aperture with the wall. No resolution has been recorded, and both offices continue to issue their respective returns.

Procedure and the Provisional Canon

The Bureau's ordinary procedure is to receive a return from a spiral, compare the designation on the return against the designation of first appearance, and either confirm the designation or issue a notice of drift. Notices of drift are addressed to the spiral in which the drift occurred and are copied to the Bureau of Spatial Designations and to the Office of Onomastic Consistency. A notice does not compel correction; it records that a correction is owed, and the Bureau maintains a register of corrections owed which at last count ran to some four hundred entries, the oldest of them concerning an aperture on the second gallery that no longer presents.

Where an aperture bears a designation for which no return of first appearance can be found, the Bureau applies Advisory Bulletin 519-Λ, granting the designation provisional canonical status on the basis of internal consistency. This is the Bureau's most frequently invoked instrument and its least popular with the Bureau of Axiomatic Purity, which has twice observed that a designation can be internally consistent and still wrong. The Bureau does not dispute the observation. It notes only that it has no other instrument.

Holdings

The Bureau's four rooms contain the following, as enumerated in its Inventory of the Ninth Landing, revised annually under the Ordinance of Continuous Inventory:

• One thousand and forty designation plates, of which two hundred and nine are held under seal pending resolution of the Plate Question's remaining cases;
• The opening ledger, forty-one volumes, of which volume one is in Vasp's hand;
• The register of corrections owed, four hundred and three entries at last revision;
• One Attenuation Lens, borrowed from the Geometric Bureau in the year 3,440 and not returned, its return having been made contingent on a resolution that has not been reached.

The Lens is kept in the fourth room and is not used. Visitors are asked not to move it, as its position has been recorded.