Calendar of Stacks

The Calendar of Stacks is a dating instrument maintained by the Librarians for recording the acquisition, movement, and recension of holdings on the numbered floors of the Tower. It is not a calendar of days. Its units are the stack, the run, and the lift, and it is used chiefly to date the Influx of the Unnumbered and the subsequent dispersal of unnumbered material into numbered ranges. The Calendar is administered from the Office of Stack Chronology on Floor 41,002, where its working tables are kept in a locked press to which two curators hold separate keys.

Officially the Calendar of Stacks is a documentary schedule only. In practice it has acquired authority over the physical ordering of the Tower, a development no drafting body appears to have intended.

Origin and structure

The Calendar was promulgated by clerkss of the Seventh Recension in the forty-first year of the Third Librarianate, as an annex to the Concordance of Acquisitions. Its first table assigned a stack-interval of eleven days to each new arrival, calculated from the day the holding was accessioned rather than the day it was shelved. The distinction caused trouble at once. Holdings accessioned in one quarter and shelved in the next fell between intervals and were assigned, by Clause 12, to "the nearer interval, regardless of direction," an instruction described by the Overlook Committee in its 704 report as "a rule that could only be written by someone who has never carried a box."

Three units govern the reckoning:

• Stack — the interval between two accessions recorded on the same run of shelves.
• Run — a continuous sequence of floor markings, terminated by a landing or a locked door.
• Lift — any vertical movement of a holding between runs, counted separately and dated separately.

The lift count was added in the Ninth Recension after the Dispute of the West Landing (Floor 9,204, winter of that year), when a consignment was recorded as arriving at its stack before it had been carried up. The consignment, a crate of unopened survey returns, was later found to have been logged in at the receiving stack while still on the landing below, and the discrepancy held up three floors' worth of accessions for a season.

Relation to the Tower's other reckonings

The Calendar of Stacks does not displace the Tower Calendar, and the Administrative Calendar continues to govern ordinary dating within the Tower. The Stacks reckon only the holdings. Where a document must bear both, the Concordance of Dual Dating, Annex 2, requires the form stack/run/lift followed by the year of the applicable calendar, separated by a semicolon. Clerks who invert the separator are required to re-date the document in the presence of the Registry of Corrected Dates.

The relationship to the older systems is strained. The Omicron Calendar's civil use and the Ascendant Calendar's displacement of it are both matters for the Calendar of Observances; neither supplies a stack unit. The Provisional Calendar carried forward the Omicron's open entries without conversion, and some of those entries are stack entries — a fact the Office of Stack Chronology did not discover until the Audit of Carried-Forward Entries of Year 896, which found sixteen stack intervals filed under days. The Office's position is that these entries were never days and so required no conversion. The Provisional Calendar article disputes this on its face.

Certain older observances are still fixed by stack rather than by date, notably the Observance of the Sealed Run, held whenever the fourth run of Floor 12,880 is closed for recension, which may fall twice in a year or not at all. The Standard Calendar of Observances lists it with a footnote reading "by stack, not by day."

The counting controversy

The principal scholarly disagreement concerns whether the initial landing of a run is counted as stack one or as the threshold before stack one. The Second Recension counts the landing; the Fourth Recension does not, having renumbered from the first shelf proper. The two recensions are both in force, in different vaults, and the Calendar's printed tables carry a marginal note instructing the reader to "consult the recension appropriate to the run," without saying which that is.

"Where a run begins at a landing, the landing is not a stack. Where it begins at a shelf, the shelf is the first stack. Where the two cannot be distinguished, the counter shall date from the landing and note the doubt."

— Fourth Recension, Clause 9

The Third Recension had ruled the opposite and was suppressed in the same decade; copies survive in the Vault of Superseded Tables and are consulted by permission of two Librarians. Curator Adelheid Voss of Floor 41,002 argued in a circulated memorandum of Year 913 that the discrepancy accounts for an aggregate drift of some 4,100 stack units across the middle floors, and proposed a reconciliation table. The table was accepted. The drift was not corrected, on the ground that the correction would itself require a recension.

Stack dating in practice

In application the Calendar is straightforward and frequently resented. A holding receives its stack date on accession, a run date on shelving, and a lift date if it moves vertically; all three appear on the Slip of Three Dates pasted inside the cover. A holding moved sideways along a floor acquires a corrected run date but keeps its original stack date, a rule introduced after the Lateral Movement Question of Year 861, when a consignment on Floor 22,415 was re-dated seven times in a single season and the shelves were left with labels that agreed with nothing.

Visitors to the stacks are asked not to carry holdings between floors. Lifts are dated, and a visitor who carries a volume up a stairwell has created a lift without a lift date, which must then be resolved by the curator on duty.

Current standing

The Calendar of Stacks is in force throughout the numbered floors and is cited in the Deep Stacks Expeditionary Corps' standing instruction to provide dual dating for all reports, the second date being the applicable Staircount Circuit and Step. Expeditions returning from below Floor 90,000 have reported shelves marked in stack intervals that do not correspond to any recension, and returns from those depths are filed under "unreconciled" pending a tenth recension. No tenth recension has been drafted. The Office of Stack Chronology notes that it has been asked to draft one eleven times and has not yet been able to establish which landing to start from.