Lateral Indexing School

The Lateral Indexing School is the collective name given to a loose body of cataloguers, surveyors, and stair-adjacent scholars who hold that a holding's true position is determined not by its floor number but by the lateral distance between it and the nearest transitway. The School has no founding charter, no register of members, and no single seat; its opponents note that it has never needed any of these, since its method can be applied anywhere there is a corridor. Its principal claim — that "a number is a guess; a span is a measurement" — is attributed to the surveyor Hesper Ambly, who is said to have scratched it into the lintel of a service door on a floor she declined to number.

Doctrine

The School's position rests on a distinction between vertical and lateral address. Vertical address, in its account, is administrative: assigned by office, subject to revision, and frequently disputed at the level of the individual shelf. Lateral address is physical. A holding stands some measurable distance from a wall, a stairwell, or a governed transitway, and that distance does not change when the Concordances are amended.

From this it follows that indexing should proceed outward from transitways rather than downward from floors. The School's surveyors speak of a holding's reach, meaning the shortest lateral distance from the item to a Lateral Stack boundary, recorded in spans to two decimal places. A holding with a reach under one span is said to be close-held and is indexed first. In principle the method is exhaustive; in practice, as Lateral Shift observations accumulate, reaches must be resurveyed, and the School's field manuals are among the most heavily corrected documents in the archive.

Relationship to the Tetra-Lateral Accord

The School's fortunes are inseparable from the Tetra-Lateral Accord, the foundational legal instrument governing lateral transitways between Lateral Stacks. The Accord does not name the School, but its schedules presuppose exactly the kind of measurement the School advocates, and the Lateral Cataloguing Guild — within whose jurisdiction the West Lateral Stacks fall — has long employed School-trained surveyors while formally declining to endorse the School's doctrine.

This arrangement was tested in the winter of the year the Guild recatalogued the western transitway verges. A survey party under Orison Pell, working to School method, reported that eleven holdings formerly indexed to a single floor lay within one span of two different transitways and were therefore, on the School's own logic, double-addressed. The Guild's response was to file the survey as evidence, take no decision on it, and direct that all eleven items be shelved in the interim at the midpoint between the two transitways. The midpoint fell inside a load-bearing pier. Nine of the eleven were re-shelved above the pier; the remaining two were declared held by the Lateral Annex school of thought and have not been consulted since.

Dispute with the School of Literal Indexing

The sharpest opposition comes from the School of Literal Indexing, which holds that a text's NDU score rises artificially simply because it is frequently cited by later works, and that a holding's place in the catalogue should follow the plain reading of its designation rather than any span measured on the ground. The two schools agree on almost nothing except that Lateral Chronologies are inadmissible as evidence, a point on which they have been jointly overruled twice.

The dispute is procedurally ancient. In the reading given by Concordance 88, Annex 2, lateral measurement is "admitted as corroboration, never as address." Concordance 104, Annex 2 — identical in wording, differing only in a marginal correction dated some decades later — is read by the School as having struck the words "never as address" in favour of "and where corroborated, as address." The correction is not initialled. The Provisional Indexing Guidelines favour the narrower reading, while the Progressivist School of Nomenclature has repeatedly cited the School's survey data in support of its own case for revising the current Tower Cycle designation, a use the School has neither endorsed nor prevented.

"The span does not care which floor it is on. Neither, on the whole, do I."

— Hesper Ambly, Field Notes, Second Recension, entry for an unnumbered corridor

Method in practice

Survey work is conducted by pairs, one holding the tape and one recording. Tapes are marked in spans on one face and in conventional vertical measures on the other, and the School requires that both faces be read aloud at the start of each survey, so that a misreading may be caught before the walk begins. Records are kept on slips of a standard green stock; the School has used no other colour since the Department of Metaphysical Holdings returned a batch of cream slips on the grounds that they could not be distinguished from holdings that had been misfiled and subsequently recovered.

The School's field inventory for a single reach is short enough to quote in full:

• the tape reading, both faces;
• the names of the two nearest transitways;
• the reach in spans, to two decimal places;
• the number of the floor on which the walk took place, entered for reference only.

That last entry is the source of most of the School's internal quarrels. Purists argue it should be omitted entirely; the surveyors who walk the corridors argue that a record without a floor number cannot be found again by anyone who was not present, and the compromise — entering it, but in a smaller hand — has held since the Desk of Lateral Correspondence ruled on the matter without issuing a written opinion.

Criticism and standing

Critics observe that the School has never produced a complete catalogue of anything, that its reaches require perpetual resurvey, and that its claim to have indexed the Thirteenth Stairwell rests on a survey whose tape was later found to have been knotted. The Guild of Lateral Navigators has declined to certify School surveyors, though it permits them to travel on navigational business provided they do not measure during the ascent.

The School has never sought formal sanction from the Indexing Guild, and no Concordance extends it recognition. Its standing therefore rests entirely on the fact that its surveyors are the only people in the West Lateral Stacks who can say, when asked, exactly how far away a thing is. Requests for this information are frequent. The School answers them in writing, on green slips, for a fee it has never revised and does not appear to collect.