Coherence Monitoring

Coherence Monitoring is the collective body of practices by which the Tower ascertains, at stated intervals, whether a thing remains itself. It is distinguished from the several practices that merely watch a place — Environmental Monitoring principal among them — by its object: Coherence Monitoring watches not conditions but identity, and it watches it on a schedule. The distinction is old, frequently restated, and still contested at the margins. Where a stairwell is monitored for dust, it is being environmentally monitored; where the same stairwell is monitored for continuing to be the stairwell it was catalogued as, it is being coherence-monitored, and a separate form is required.

The practice is overseen in its doctrinal aspect by the Librarian of Coherence, who maintains the Protocols for Coherence Assessment, and in its operational aspect by the Directorate of Archival Coherence, which issues the Material Coherence Attestation on which most monitoring findings ultimately depend. Routine field returns are lodged with the Bureau of Procedural Coherence and, where the finding is contested, referred onward to the Committee for Catalogical Coherence, whose rulings are published as Coherence Directives.

Origins and the Decree of Environmental Coherence

Coherence Monitoring was not named as such until LY 340, when the Decree of Environmental Coherence authorised the expansion of the Bureau of Environmental Cohesion and the formalisation of Environmental Monitoring. The Decree is remembered chiefly for the expansion; its third schedule, four lines long, is remembered for the sentence that founded the present discipline: "Nothing shall be monitored for condition alone, lest its condition be found to have outlived its identity." The Directorate of Environmental Coherence has argued ever since that this clause was drafted to limit its own remit rather than to create a new one, and has never conceded the point.

The first coherent-monitoring returns, filed on 12 Nivôse of the following year, covered eleven landings and forty-three objects, of which nine were found to have drifted from their catalogue descriptions without any corresponding change in appearance. The clerk who filed them, Ondrej Vask, appended a note that has been quoted in every subsequent manual: "The shelf is the same shelf. It is no longer the same shelf." Vask was reassigned to the Attenuation Galleries shortly afterwards and did not file again.

Intervals and the problem of the second reading

Coherence Monitoring proceeds by interval. A thing monitored once has been inspected, not monitored; the practice requires at least two readings separated by a stated period, and the period must be entered in the register before the first reading is taken. This requirement is the source of the Tower's longest-running procedural quarrel. Concordance 33 fixes the intervals for the Ongoing Monitoring of the Attenuation Galleries at ninety days, while Concordance 41, drafted eleven years later, holds that no interval may exceed sixty days for any object above the four-hundredth floor and sets no limit at all below it.

The contradiction has never been resolved, and both readings remain in force depending on which office receives the return. The Monitoring Niche, which holds oversight authority under Concordance 33, has taken the position that its own intervals are the only intervals, describing Concordance 41 in a circulated minute as "advisory in character and aspirational in arithmetic." The Directorate of Archival Coherence declines to comment on intervals and will accept returns on either schedule provided the attestation is signed in the same hand as the register entry.

"Where two intervals are lawful, the longer is not the more lawful, nor the shorter the more diligent; the monitor is bound only to say which he kept."

— Librarian of Coherence, Protocols for Coherence Assessment, Protocol 9

Intermittent Coherence and the third reading

A minority of objects do not hold a stable coherence between readings. They oscillate, and the practice recognises this under the heading of Intermittent Coherence, which requires a third reading taken without notice. The third reading was introduced after the Vashti Landing incident of LY 612, in which a staircase was attested coherent on eleven consecutive inspections and found on the twelfth to be a room. The monitor had given notice of every visit. The Ambience Monitoring Corps, created to patrol non-catalogued landings, now supplies the unannounced readings for the practice, and does so without informing the landing in question, which is considered good manners rather than a rule.

Intermittent returns are the most expensive in the archive to process, since each requires a Modal Coherence Attestation in addition to the material one. The Office of Material Coherence has twice petitioned to have intermittent objects transferred wholesale to the Chamber of Dimensional Coherence; both petitions were refused, the second on the grounds that the Chamber monitors rooms and not shelves.

Instruments and the Glyph

Field monitors carry no instrument but a register, a seal, and the Glyph of Applied Coherence, a small mark struck against the object's catalogue plate on each visit. The Glyph is not a measurement. It records only that a monitor stood before the object on a given day and found it to be what the register said. Where the Glyph is later found struck twice on the same plate without an intervening reading, the return is void and the monitor is asked to explain the gap in writing.

The Guild of Applied Coherence guards the striking of the Glyph and has refused, since LY 588, to permit its use on any object that has not previously received a Material Coherence Attestation. The refusal has left a class of roughly two thousand unfortunates — objects catalogued but never attested — which may be monitored in principle and marked in no way whatever. Monitors assigned to them record the readings on loose paper and keep the paper about their persons. It is generally understood that these readings will be misfiled.

Coherence depletion and current practice

Where an object's readings diverge beyond tolerance, the sector is referred to the Clarity Depletion Monitoring Unit, which has monitored sectors experiencing Clarity Depletion since the practice was regularised. The Unit's returns are the only ones in the Tower that are counted rather than filed, and its quarterly figure is read aloud in the Buffer Archives on the morning it is posted.

Since 25 Vendémiaire the practice has been supplemented by the Circulationist pilot program, under which the Migrating Map serves as a real-time structural monitoring system for the eastern spiral and reports coherence drift as it occurs. Preliminary results are regarded as promising. The pilot's returns are accepted for all purposes except the striking of the Glyph. Monitors assigned to the pilot have been instructed not to carry loose paper.