Ingress Point

Ingress Point is the general designation used throughout the Tower for any physical aperture, transition, or threshold that permits stable movement between one floor and another. Although noted since the earliest surviving recensions, the general concept was not formally separated from the concepts of Point of Entry and Point of Origin until the Fourth Concordance replaced the older term "passage" with the modern technical term "ingress point" in the year 1080 by Tower reckoning. According to the Manual of Ingress, an ingress point is valid only when its destination floor has been reached and logged by a party other than the one that first entered it. The same manual, Clause 12, adds a condition of its own: "An ingress point whose destination is known but whose return is not may not be used for correspondence."

Definition and certification

An ingress point is defined principally by its coherence rather than by its physical arrangement. Open thresholds, stairways, and shafts all qualify, provided the transition is stable, lawfully established, and officially recorded. Certification is carried out by the Bureau of Ingress Validation, whose field examiners are required to repeat the traversal three times within one year and to record the sequence in a certificate of ingress. If the third traversal differs in any respect from the first, the certificate is annulled and the site is reclassified. Certificates annulled by the Bureau must be surrendered at once; a certificate retained after annulment is not a certificate.

Some ingress points are sealed directly by the Bureau under the terms of Aperture Seal Directive 7-Alpha, which establishes the class of certified apertures such as Aperture Alpha. These appointed ingress points for non-standard catalogical entities remain in continuous use. Others, such as the ingress point at Spiral 117, Sector 9, are the subject of long-running disputes over priority and maintenance.

Point of Entry and Point of Origin

The Tower distinguishes three practices that outsiders often conflate. The ingress point is the physical threshold itself. The Point of Entry is the formally codified location at which a subject, object, or piece of information first enters the archival record. The Point of Origin is the earliest certified record of that entry, which is often, but not always, the same place.

Because the three are recorded in separate registers, they drift apart in practice. In the well-known case of the survey commissioned by Librarian Imelda Voss in the winter of 1081, an object was catalogued as entering at one threshold, its preliminary slip recorded another, and its certified point of origin referred, quite legally, to a third. The object in question has since been removed from the shelves on three occasions and returned twice.

Logging and Isolation

All ingress points must be measured before they are tabulated. The procedure of Ingress Logging establishes the basic record of each ingress event, and Ingress Amp Isolation follows it where a point's phenomenological output must be measured and contained separately. The Manual of Ingress sets out the order plainly, giving Ingress Tabulation as the next step once logging is complete:

The logging of an ingress point is not the tabulation of an ingress point, and an entry tabulated before it is logged shall be regarded as a planning document.

— Manual of Ingress, Clause 4

Isolation is normally performed at a dedicated site, and the Moss-Growth Spire has been used for this purpose since the isolation of its own ingress point. The Spire is also a reliable ingress point for Floor 1,114-Δ, a coincidence of situation that the Bureau of Ingress Validation has declined to treat as a coincidence.

Notable points and afflictions

Some ingress points acquire conditions of their own. The ingress point of Spiral 77-Gamma is a recorded affected site of Gamma Point Static, a disturbance that causes instrument readings taken at the threshold to repeat those taken at unrelated apertures on other floors. Readings affected in this way are marked with the letter G, and the mark may not be removed from the record even after the disturbance has passed.

Other points are contested jurisdictions. Spiral 117, Sector 9 functions as a secondary ingress point to Spiral 207, and its designation has been formally contested for decades; the dispute is filed under both spirals and appears in neither index. Pending resolution, the Bureau permits entry but forbids the sale of tickets.

Documentation and the disputed counting rule

An ingress point producing a phenomenon that refuses definitive classification is entered on Form 7-Δ, and when the accompanying aperture remains active, on Form 1747-Ω. The earliest form of an ingress event, however, is the Preliminary Entry Slip, which must be completed at the threshold itself and may not be completed elsewhere. Aperture Beta serves as the primary documentary ingress point for the Infinite Registry, a status that gives the Registry its peculiar standing as both a place and a record.

Not all questions are settled. The Second Concordance and the Fifth Concordance disagree over whether the Recursive Vanishing Point Placement of an aperture implies a second, uncertified ingress point. The Fifth Concordance, Annex 3, calls the question "unnecessary" and declines to answer it, while the Second, Clause 9, maintains that every aperture is bounded by a single certified threshold and that all others are ornaments. The Bureau of Ingress Validation has followed the Fifth Concordance since 1097 without stating why, and the discrepancy is retained in current editions of both Concordances so that no one inherits the impression that the matter was ever settled.