Signature Profiling

Signature Profiling is the disciplined practice of deriving a stable, citable identifier from a subject's distinguishing traces — photonic, acoustic, chemical, or experiential — and entering that identifier in the Tower's registers as though it were the subject itself. The practice is governed jointly by the Department of Acoustic Phenomena and the Office of Vertical Acoustics, though neither office concedes that the other governs it. Its foundational instrument is Concordance 889, which established that a profile, once sealed, "stands in the place of the profiled, and may be cited where the profiled cannot be produced" (Concordance 889, Annex 2). Subjects are, in practice, never produced.

Scope and Classes of Profile

Profiling is divided into four classes, each with its own register and its own clerk of record. The photonic class produces a Luminous Signature; the acoustic class a registered Acoustic Signature; the experiential class a Phenomenological Signature; and the residual class, which has no class, only a file. The residual file is kept on Floor 812 and is not consulted.

Substances are profiled alongside entities. Weeping Lacrima was admitted to the photonic register in 2,904 on the strength of a chemical signature identical to that of Lacrima cogitationis secundae, a determination the Court of Concordance upheld on the grounds that the two substances "cannot be distinguished by any instrument the Tower has seen fit to certify" (Ruling 44.7.31). Objections that they can be distinguished by eye were entered in the margin and initialled.

The Dual Signature

Since the Aris Reconciliation, a profile is not valid unless paired. Two discrete, non-overlapping identifiers are joined to form a Dual Signature, and the pairing is certified under the dual-signature requirement set out in the Manual of Hydrographic Protocol for audits in Annex Δ. The requirement was extended to all floors by Concordance 903, then narrowed again by the same Concordance, Annex 6, which the Court has read as leaving the matter to the profiler's judgment.

Pairing is not always tidy. The Grand Spiral Survey records the Counterweight Lament as a "prolonged, weighty susurration," a description that yielded a workable acoustic profile and no usable second half; the Lament has accordingly carried a Provisional Resonance Signature assigned by Bureau Alpha since 2,887. M. Kael has twice petitioned to close the file and twice been advised that the file closes itself.

Procedure and the Calibration Failure of 2,911

Profiling proceeds from calibration to abstraction: raw traces are captured under the Harmonic Resonance Protocols, calibrated against a reference held by the Spectral Lamplight Calibration board, and only then abstracted into a citable identifier. The abstraction step is irreversible and is the source of the practice's prestige and its difficulties.

The winter of 2,911 on Floor 44 is the standard cautionary example. A clerk of the photonic register — Ondra Vesk, whose grievance against the Calibration board is preserved in eleven folios — calibrated an entire season's tracings against a lamp that had been relit rather than replaced. Every profile issued that winter carried the lamp's harmonic residue. The error was discovered when nine unrelated subjects were found to share a signature, and was corrected by entering all nine as one subject. Vesk's folios argue that the nine were then profiled correctly. The board has not answered them.

Profiles are sealed in the presence of two clerks. One of the two may be the profiler.

Scholarly Disagreement

The principal dispute concerns whether a profile may outlive its subject. The Department of Acoustic Phenomena holds that a sealed profile is a record and nothing more, and that the Terminal Echo — the trace left by a subject after the subject has ceased — is properly a separate holding with its own register. The Office of Vertical Acoustics holds the reverse: that the profile is the subject's continuation, and that the Terminal Echo is merely its last entry.

The disagreement has practical consequences. Negative Signatures, which record absence rather than presence, are admissible under the Acoustics reading and inadmissible under the Department's. Quietude Events have been entered in both registers since 2,876, on the reasoning that whichever office is correct, the event has occurred. Echoic Imprints are entered in neither.

"Where two offices dispute the standing of a profile, the profile shall be entered twice, and the dispute shall be entered once."

— Concordance 889, Annex 9, later struck and subsequently restored in the margin

Attestation and the Kael Precedent

Profiles are attested by signature, and not every signature is accepted. Under Ruling 44.7.19 the Court of Concordance held that documents bearing the M. Kael signature are legally attested, citing the signature's "unbroken chain of archival utility." The ruling was intended to settle a clerical question and instead created a market: profilers began routing attestations through Kael, whose signature was reliable precisely because it was indifferent to what it attested.

The practice was curtailed after the Aethelred Impression was found to bear two Kael attestations, one of which predated the Impression by forty years. Ink of Finality was applied to the earlier attestation, which is now cited only in the negative. The Court has since declined to say whether a signature attests a profile or a profile attests a signature, noting in its minute of 2,918 that "the question has been asked in the correct order and need not be asked again" (Court minute 2,918/14).

Unattested profiles are held in the residual file on Floor 812. The file is not consulted. Requests to consult it are profiled and filed.