AC-I (General Illumination)

Definition and scope

AC-I (General Illumination) is the standard class designation for Attenuated Cultivar authorized to serve as the default ambient light source on floors not otherwise exempted by the Illumination Protocols. It is the reference class of the entire cultivar system: every other designation in the Attenuated Cultivar taxonomy — AC-II, AC-IV, AC-VII — is defined by deviation from AC-I rather than by intrinsic property. The designation appears in the Master Illumination Schedule as the standing entry for all unlisted areas, which means that in practice AC-I governs roughly four-fifths of the Tower's catalogued floor area.

AC-I refers specifically to lumen-moss, the most common cultivar class in the Tower. Its permitted use is stated in Concordance 11 and verified annually under the Illumination Audit, with the Committee for Sustained Illumination holding authority over seasonal adjustment of its deployment.

Technical standard

The governing parameters of AC-I are set out in Annex 3 of Concordance 11 and are restated, with modifications, in the Fourth Recension of the Illumination Protocols. The four controlling figures are:

The decay figure is the one most frequently cited and most frequently misread. It governs the cultivar as a population, not as a surface: individual patches may go dark entirely provided the mean across a registered zone remains within tolerance. Inspectors have historically disagreed about how to treat zones with uneven substrate, a dispute that produced the Standing Interpretation of Lumen Zones (Annex 7, Second Recension), which holds that a zone ends where the plaster seam is.

Relation to the Illumination Audit

AC-I is the class against which the Illumination Audit is principally conducted. Because AC-I is the default entry in the Master Illumination Schedule, an error in that entry propagates to every unlisted floor simultaneously; the Audit therefore devotes a disproportionate share of its findings to this single line. The Department of Sustenance and Illumination has noted in three successive reports that a corrected AC-I entry rarely requires re-inspection of individual floors, since the floors were never non-compliant — only the schedule was wrong.

The Audit also confirms adherence to Single-Source Illumination, under which a registered zone may draw from one cultivar source only. AC-I zones are accordingly prohibited from co-existing with Resonance Lamps on the same wall run, a rule occasionally tested by floors that inherited both fixtures before the Illumination Protocols were recensioned.

Institutional history

The designation AC-I predates the formal cultivar taxonomy. Early records refer to it simply as "the general moss," and the alphanumeric form appears to have been introduced during the compilation of the First Recension of the Illumination Protocols, when the Office of the Archivist-General required a shorthand for aggregate scheduling. The letters were chosen, per the marginal note of Registrar Thessaly, "for sorting, not for meaning." Prior to this, references appear in the registers of the Librarian-General as "ordinary light, to be maintained."

A prolonged jurisdictional dispute between the Committee for Sustained Illumination and the Department of Sustenance and Illumination over who certifies substrate composition was settled by General Order 4,417, which assigned verification to the Committee and re-inspection appeals to the Department. The arrangement has held, though both offices continue to circulate their own annexes on the same subject.

Known points of contention

Two questions remain unresolved in the record. The first concerns whether AC-I may be applied to vertical runs exceeding eleven metres; Concordance 11 is silent, and the Illumination Protocols' Second Recension permits it while the Fourth Recension omits any mention. The second concerns decay measurement in unheated passages, where the Committee for Sustained Illumination's quarterly method produces figures that the Office of the Archivist-General has twice declined to enter into the register pending clarification.

Floors wishing to depart from AC-I must petition under General Order procedure and await concordance by the Librarian-General. Successful petitions are rare; the most frequently cited precedent remains the exemption granted to a single stairwell on the grounds that its occupants "did not require to read."

"Where no other class is named, AC-I is in force. Where two classes are named, the lower number prevails. Where two instances of the same number are named, the record is to be corrected."

— Concordance 11, Annex 3, Clause 2

Custodial staff are reminded that lumen-moss substrate must not be watered during the hours of the Audit, and that any patch reaching Anomalous Grade is to be reported to the Committee for Sustained Illumination rather than scraped.