Article VII, Annex Δ

Article VII, Annex Δ is the fourth and least consulted annex to Article VII: On Non-Euclidean Infrastructure, appended in Cycle 89 under the authority of the Seventy-Fourth Concordance and confirmed, with reservations, by Annex VII of the Ordinance on Rotational Infrastructure. It governs the treatment of interstitial volume: the space that a non-Euclidean structure encloses without possessing, and the obligations owed to persons who find themselves inside it.

Unlike its companion annexes, Annex Δ carries no schedule of load tables and no procedure for inspection. It consists of nine clauses and a single diagram, and its subject is not architecture but occupancy.

Definition of interstitial volume

Clause 1 defines interstitial volume as "any measurable region bounded by a structure and not contained within it." The phrasing is deliberately circular. A corridor whose two ends are adjacent encloses a region — the region between them — which the corridor does not itself include; that region is interstitial, and Annex Δ asserts jurisdiction over it. The Department of Calibration has objected at intervals that the definition is unfalsifiable, on the grounds that any bounded region can be described as both enclosed and excluded depending on which wall is nominated as the boundary. The objection is recorded in Third Concordance, Annex VII and has never been formally answered.

The annex further distinguishes interstitial volume from declared volume, which is the volume a structure reports of itself. Where the two disagree, Clause 3 provides that the declared volume is presumed correct until an occupant produces a measurement. This has been read as placing the burden of proof on whoever is standing in the room.

Obligations of occupants

Clause 4 sets out the three obligations of a person present in interstitial volume:

to record the number of doorways observed on entry and on exit, and to report any discrepancy to the nearest Custodian;
to refrain from marking walls, floors, or ceilings, including by measurement;
to leave by the aperture used to enter, unless a second aperture has been certified under Annex VII on Intersection and Right-of-Way.

The prohibition on marking is the annex's most enforced provision. The Bureau of Motive Compliance has ruled on eleven occasions that a chalk mark constitutes an alteration of the interstitial fabric, and that a pencil mark does not, on the reasoning that pencil is provisional. The distinction is not explained and has been criticised in every subsequent commentary.

The Diagram of Nine Openings

The single diagram accompanying the annex depicts a square room with nine openings, three to a side, each labelled with a lowercase letter. No legend survives. The Guild of Resonant Masons has maintained since Cycle 91 that the diagram is a plan of the room in which the annex was drafted, and that the letters are the initials of the nine clerks present. The Department of Calibration holds instead that the diagram is schematic and that the letters denote the nine permitted directions of egress, of which only one is ever correct at a given moment.

Neither reading can be tested, because the annex does not state where it was drafted. Chief Scribe Elara of the Third Spiral is recorded as having reviewed the text in draft but did not sign the diagram, and her marginal note — "nine is generous" — is the only contemporary comment extant.

Interaction with Protocol VII

Because interstitial volume cannot be reliably ventilated, Protocol VII applies to all work conducted within it, and oversight falls to the Sigma Regulator under Article VII of Security Protocol Sigma. Practically, this means that any measurement campaign in interstitial volume must be conducted within a controlled atmosphere carried in, which many survey teams regard as making the measurement impossible and the obligation therefore satisfied by default.

Annex Gamma, Section VII was enacted partly to resolve this difficulty and instead compounded it: it requires that the controlled atmosphere itself be measured, and that the measurement be taken within a controlled atmosphere.

Dispute over precedence

A standing disagreement concerns whether Annex Δ is subordinate to the Third Concordance's Article VII on Material and Metaphrastic Integrity or parallel to it. The Fourth Order maintains that the annex is a gloss on the Third Concordance and yields wherever the two conflict; the Bureau of Motive Compliance maintains that Annex Δ was enacted later and therefore displaces the earlier text within its own subject matter. Concordance 42, Annex Gamma, Section VII is cited by both sides.

The Seventh Chime has twice been rung to close debate on the question. On both occasions the Chime closed the session without resolving the precedence, a result the Librarians have recorded as "customary."

"The annex does not say what happens to a person who is in the volume when the volume is reclassified. It says only that the person was in it. That is the whole of the guarantee, and it has proved sufficient."
— unattributed commentary, shelved with the clasped appendices at Floor 4,112