Codex Descriptivus

Codex Descriptivus is the administrative register prescribing the mandatory fields of every catalogue entry in the Tower. It is not, properly speaking, an encyclopedia of anything; it is a form with a very long history. Its full descriptive entry is used in the Subject Stability Assay, and no entry may be admitted to the shelves until it has been checked against the Codex and found to declare, at minimum, a Provisional Designation, an Ontological Class, a Primary Floor of Residence, and such Cross-References as the case requires.

The Codex is held in the Scriptorium of Fixed Forms, Floor 3,114, in a locked cabinet whose key is kept in the cabinet.

Structure and the Four Required Fields

The body of the work consists of four principal schedules, one for each required field, followed by a long tail of annexed schedules for fields that were once required and are no longer, or were never required and have never been successfully removed. The schedules are numbered I to IV, and each is written in the interrogative: the form asks, the catalogue answers, and the Librarian inscribes. A fifth schedule, for Cross-References, is bound out of sequence between II and III by an error of the Second Recension of the Formulary that no one has been willing to correct.

The Codex distinguishes throughout between description — what an entry says a thing is — and designation — what the entry says it is called. The distinction is preserved in the article despite three separate attempts to collapse it, most recently in the Year of the Misshelved Codex, when the collapse was attempted, badly, by wholesale re-shelving.

History of the Recensions

The Codex exists in nine recensions. The first, First Recension, required only a name and a floor. The fourth, prepared under the authority of the Bureau of Fields and Descriptors, required eleven fields, of which four proved answerable. The seventh, following the principles of the Codex Classificatorius as those were then understood, required the same four fields but required them twice, once provisionally and once on confirmation, which doubled the labour of the catalogue without doubling its precision.

Dispute over the number of recensions continues. The Eleventh Concordance treats the present text as the ninth recension; the Twelfth Concordance, annex 3, refers to "the tenth, being the ninth as amended." The Bureau has declined to resolve the question, noting that the two statements are both on file.

Relation to the Deterministic Codex

The Codex Descriptivus is frequently paired in citation with the Deterministic Codex, and the pairing has caused difficulties. The Deterministic Codex is an object as well as a text — the apparatus recovered during the Year of the Misshelved Codex — and the Misshelved Codex turns to folio 271 when brought within five metres of it. Clerks preparing descriptions of the apparatus have therefore been caught in a recursion of citation: describing the Deterministic Codex requires the Descriptivus, which requires them to describe the Deterministic Codex. A working note in the Scriptorium forbids this; it is headed "Do not describe the apparatus while holding it," and it is signed only with an initial, R.

"A description of a thing shall not be held to be the thing, nor the thing the description, nor either the schedule by which the description is filed."

— Seventh Concordance, Annex 2

Use in the Subject Stability Assay

The Assay is conducted by reading an entry's full description in the Codex against the subject it purports to describe. Where the entry and the subject agree, the subject is stable. Where they diverge, the Assay records the divergence and the entry is amended, not the subject. Clerk Maret Voll of the assay office has argued in a memorandum of 14 October that this ordering is "backwards on its face," and has been asked three times to withdraw the phrase. The phrase stands; the memorandum does not.

Criticism and the Field Dispute

The principal criticism of the Codex is that the four required fields do not exhaust the things that must be said. The Tower's Compendium of Minor Contradictions records some four hundred instances in which an entry, correctly completed, was found on reading to describe nothing at all. The Alastorian Codex objects specifically to the Ontological Class schedule, on the ground that it classifies by resemblance rather than by kind, so that the Somatic Codex and the Aortic Codex were at one period filed beneath a single class, "vascular, intermittent." The Bureau of Fields has not conceded the point. It has, however, added a field.

Visitors to the Scriptorium of Fixed Forms are asked not to read the cabinet.