Metric Inconstancy

Metric Inconstancy is the class designation under which the Tower catalogues all subjects whose measurable properties vary without authorization between one reading and the next. It is the parent heading of the four subordinate classes — Metric Instability, Metric Inundation, Metric Dissipation, and Non-Convergent Metric — and is administered not by a single office but by three that disagree with one another about nearly everything except the necessity of the class itself. Where a subject's Redefined Persistence Metric coefficient exceeds 4.0, the subject is routed to Class Ψ proper, in which the metric is suspended entirely and no further measurements are entered in the register until the suspension is lifted.

Origin and designation

The class was established by Fourth Concordance, Annex 9, in the eleventh year of the Librarians' calendar, following the so-called Sill Register incident: a routine survey of Floor 216 in which the recorded length of a corridor returned three different values on one afternoon, all of them correct. Annex 9 fixed the designation Ψ and delegated the class's working definitions to whichever office could produce a quorum first. Three offices did, within the year.

The letter is not pronounced. Librarians write "Class Ψ" and read "the class." Attempts to give it a spoken form were abandoned after the Proceedings of the 301st Colloquium on Metric Integrity, where a proposal to read it as "psi" was set aside on the ground that it would encourage abbreviation.

The three offices

Primary casework falls to the Bureau of Metric Integrity, which registers new subjects, assigns the sub-class, and maintains the standard prevention protocols. The Office of Metric Assurance recognizes five distinct stages of progression for both instability and dissipation under Edict 4117-γ, and is the office that declares a subject terminal. Assent for anything above 20 AU falls to the Standing Committee on Metric Stability, whose review is required before a subject may be entered at all.

The arrangement works badly. In the winter of the relevant year, a stairwell on Floor 512 was registered by the Bureau as dissipating, certified by the Office as inundating, and returned by the Committee to the Bureau on the ground that a stairwell is not a system. It has remained unmeasured since.

Relation to neighbouring classes

Metric Inconstancy is frequently confused with Metric Instability, which is a sub-class and not a synonym; instability names variance in the reading, whereas inconstancy names variance in what is being read. The distinction is drawn in Sixth Concordance, Annex 2, and contradicted in the same document's marginal recension, which treats the two as identical and adds a note that "the Committee will know the difference when it sees one" (Sixth Concordance, marginalia to Annex 2, unattributed).

Metric Inundation is distinguished from Metric Dissipation chiefly by direction — dissipation is the loss of a metric from a system, inundation the arrival of one where it was not asked to be — while Metric Caging is the administrative remedy of last resort, suspending a measurement procedure within a formally authorized circulatory system until the reading settles.

Procedure and its failures

Registration requires a first reading, a witness, and a sealed envelope. The envelope is not opened until the subject is either stabilized or abandoned; this is intended to prevent the reading from influencing the register. It does not always succeed. A clerk of the Bureau, Anselm Vey, assigned to Floor 344, recorded in his grievance of the fourth quarter that his envelopes had begun returning heavier than they went out, and that on three occasions the seal was already broken when he received them. His request to be reassigned to a non-measuring floor was denied, the denial citing Ninth Concordance, Annex 1, which reserves reassignment to subjects under 4.0.

Metric Recalibrators are issued to field staff for subjects below Stage Three; above Stage Three, they are not to be carried on the person, and no reason is given in any Concordance.

Unresolved dispute

The chief scholarly disagreement concerns whether Class Ψ is a class of subjects or a class of errors. Office of Metric Resonance holds the former, and was convened in the wake of the Metric Instability that followed the Cataloguing of Floor 812 specifically to adjudicate cases of this kind. The Topological Transformatives hold the latter, and have declined to enter their own instruments into the Ψ register on the ground that an instrument which changes the thing it measures is not inconstant, it is simply an instrument. The disagreement was referred to the Standing Committee on Metric Stability in the year of the Sill Register and remains open; interim guidance permits either reading provided the envelope is sealed.