Oneiric Taxonomy

Oneiric Taxonomy is the systematic classification of dream material by genus, species, and register, conducted under the authority of the Dream Registry and recorded, since the recension of 14 Sigma 402, at the point of intake rather than at the point of report. It is distinguished from Oneiric Taxonomies proper — the several overlapping classification schemes in current use — in that Onieric Taxonomy (singular) describes the discipline and its offices, while the Taxonomies (plural) are the instruments that discipline handles. The distinction is observed in all internal correspondence and in almost no external correspondence. Complaints that the two titles "cannot be told apart by the eye" are answered, where they are answered at all, by reference to the article on the subject in the Registry's own handbook, which is titled neither.

Structure of the Classification

The Registry classifies dream content across four heads: substratum, motif, valence, and echo. An item is not fully registered until all four heads are entered, though it is common for intake clerks to enter substratum and motif and leave valence and echo "pending the third sitting." Pending items are stored on the second gallery of the Registry floor in slate trays and may be consulted, once, with the sanction of a Deputy Registrar.

Classification proceeds by intersection. A sleeper who reports "a green stair that descended and kept descending" is entered under substratum architectural, motif descent-without-termination, valence neutral-to-watchful, and echo three-part, resolving. The four entries each carry a cross-reference to the others. It is at these crossings that Oneiric Feedback is most often observed to originate, a fact recorded in the Standing Note of Sub-Registrar Ovel Mann, whose own classifications (she insisted on entering valence first, against precedent) were posthumously struck from the Register in 388 and reinstated in 402 without explanation. The reinstatement was later itself struck, and restored again. Readers wishing to consult her entries should apply at the desk. The desk is usually staffed.

History

Early classification was ad hoc. The Register of Reported Oneiric Phenomena for the years 106–140 shows a single head of classification (thing seen) and a single head of disposition (noted). The earliest substantive scheme, the Nine-Head Arrangement of 171, was abandoned after two decades because heads six and seven were found to describe one another. Head six ("apparitions of known halls") and head seven ("halls that feel known") could not be assigned to any given item without the item being "tried" in both, a procedure which, per the minutes of the Arrangement Committee, "consumed an afternoon apiece."

The present four-head scheme derives from the Cadastral Recension of 366, so called because it was drafted in the survey annexe and bears a marginal diagram of a stairwell that no one has since matched to any stairwell in the Tower. The Recension's own author, one Clerk Emeric Voss, entered a codicil withdrawing the scheme seventeen days after lodging it; his superior had already countersigned. Voss was transferred to the Atlas of Oneiric Water Tables and did not return. The four-head scheme remains in force.

Contradictions in the Concordances

The Concordances disagree on the authority of the Registry to bind its own classifications. The Second Concordance, Annex 9, holds that "a classification once entered shall not be altered except by the unanimous consent of the registering office" — a requirement that has never been met, as the registering office has never been of one mind about anything, including the meaning of Annex 9. The Eleventh Concordance, Article 3, holds the opposite: that entries "may be amended at any time by the hand that entered them, and by no other hand." Practitioners have adopted the practice of amending their own entries and leaving others to amend theirs, which satisfies both documents in spirit and neither in fact.

"Both instruments cannot govern the same clerk on the same afternoon."

— Observations of the Registry, Appendix D, attributed to Deputy Registrar Heliane Fox

Fox's Observation was itself entered into the Register as a classified item (substratum documentary, motif contradiction) and is now cited both as authority and as evidence. It has been amended twice.

Interaction with the Decimal System and the Hum

Every classified item receives a sigil under the Oneiric Decimal System, and classification is not complete until the sigil is entered in the margin in Oneiric Blue. The tone the sleeper reports — where it is reported — is classified separately, under sigil 372.441, the entry for the Oneiric Hum. The Hum is not a taxon, but intake clerks have a customary habit of classifying it anyway, usually as echo, continuous, and the Registry has stopped correcting them.

Where classification produces an item of sufficient weight, the item is drawn into the substratum of a Type 5 structure and may be worked by the Oneiric Vitalists. Where it is not, it is transferred to the chamber vaults and thereafter dressed for storage by the Office of Oneiric Hygiene under seal. Visitors to the vaults are asked to leave their sigil stamps at the door.

Criticism and Departures

The chief objection to Onieric Taxonomy is that it classifies the report and not the dream. The Registry has considered this objection on eleven occasions and has each time ruled that the dream is unavailable for classification, being inaccessible in the absence of a report, "the report being the dream's only certified copy." Critics reply that this makes the discipline a taxonomy of paperwork. The Registry has declined to rule on that. The question is held, along with a number of others, in the slate trays.