Dual Cataloguing

Dual Cataloguing is the practice by which a single subject that does not exist is recorded twice within the Tower Standard Chronology Tsc, each record pursued along a separate classificatory track and lodged by a distinct hand. It is the operative method mandated for irreconcilable dual-natured phenomena and is administered under the Dual Signatures system, the Dual Recordkeeping convention, and the provisions of the Ordinance of Perpetual Transference.

Origins and Ratification

The first formal instance of Dual Cataloguing is generally held to be the filing of Entry 44Δ-742-881, which the Resolution 12 dictated be entered under two instruments signed and filed separately by distinct clerks. The dispute that produced this requirement arose from the attempted cataloguing of the Iterative Chamber, whose nature could not be settled by a single folio. The resulting settlement, the Compromise of the Dual Designation, precipitated the ratification of Resolution 12 on 17 Ventos, 842 (Post-Cataloguing). The Ninth Concordance, issued in Year 251, had earlier imposed a dual-entry system upon the Office of Atmospheric Cataloguing during the Western Atmospheric Spiral calibration crisis, though the Cartographer-Scribes maintain that this was a parallel development and not a precursor.

Procedure and the Holding Protocol

Under the Dual-Entry Protocol, the formation of a dual folio is a bureaucratic procedure of the Holding Protocol. Each instrument must name the same subject while describing it under contrary aspects; the Primary Entry is considered neither truer nor prior, only first in sequence of lodging. The Dual-Authority Charter prescribes that the two clerks be drawn from separate scriptoria, a rule that the Compromise of the Dual Designation left deliberately vague as to floor of origin. On Floor 118-Omicron the Mutable Stacks are governed by the Ordinance of Perpetual Transference, which mandates the dual cataloguing identifier practice and has produced six known contradictions with the Dual Promulgation recension of Year 372.

"No folio under Dual Cataloguing shall be amended in the absence of its counterpart; where one clerk has perished, the surviving folio enters the Dual-Chambered Reliquary pending replacement."

— Resolution 12, Clause 9, Sub-annex B

The Dual-Chambered Reliquary and Verification

Materials deferred under Dual Cataloguing are, where sovereignty is implied, lodged in the Dual-Chambered Reliquary of Implied Sovereignty, which houses the Lock of Negation. Resolution 12 specifies the forms required for requesting the Dual-Chambered Reliquary, a process the Dual-Guild Verification Protocol extends to the tactile and optical branches of Material Verification. The Dual-Phase Resonator is employed on Floor 77-Beta to test whether a deferred folio still resonates with its counterpart; a recorded null resonance in Winter 904 led to the temporary suspension of all Dual Cataloguing on that floor, lifted only when a clerk discovered the resonator had been seated upon a Class II left over from The Great Dampness.

Scholarly Disagreement

The Ninth Concordance and Resolution 12 are not reconcilable on the question of precedence. The Ninth Concordance holds that the atmospheric dual-entry system established in Year 251 supersedes later folios where spiral calibration is concerned; Resolution 12, promulgated in Year 372, requires that dual promulgations be filed under the Dual Signatures system with each instrument signed and filed separately by a distinct clerk, making no exception for atmospheric matters. The Cartographer-Scribes have proposed a third track, the Conceptual Laminates method, under which a subject is layered rather than duplicated; the proposal was rejected by the Librarians on the grounds that it created "a thickness without a second clerk."

Incidents and Annex Disputes

On 3 Serral, 887, Clerk Ovin of the Lower Scriptory filed both instruments of a dual catalogue for the Unreturned Stairwell, an act the Dual Signatures practice forbids. The error was discovered when the Dual Recordkeeping office noted that the two folios employed the same ink batch. Ovin's defence — that the stairwell "descended and ascended simultaneously and thus resembled a single act" — was recorded but not accepted. The folios were transferred to the Dual-Chambered Reliquary and Ovin was assigned to recopy the Tower Standard Chronology Tsc by blunt stylus for the remainder of the year.

A visitor may not bring a writing implement taller than eleven inches into any chamber where Dual Cataloguing is in progress, as the practice requires both clerks to maintain eye level with their separate folios.