Seven Metrics of Potentiality

The Seven Metrics of Potentiality are the standard schedule of quantities by which Potentiality is measured, tabulated, and reported within the Tower. They are set out in Annex 2 to the Sixteenth Concordance and have been recensioned, in whole or in part, eleven times since their first promulgation under the Year of the Script 188. The Metrics are administered doctrinally by the School of Perpetual Potentiality, which maintains the master register on Floor 201, and are audited in their application by the Curators of Anomalous Metrics on behalf of the Department of Ambiguous Metrics. The unit common to all seven is the Ardor.

The Seven Metrics

The Metrics are numbered and are never cited by name alone; the Sixteenth Concordance, Annex 2, §3, requires that the numeral precede the name in all filings. The schedule as currently received is as follows:

• Metric I — Latency: the interval between a possibility's registration and its first exhibition in a reading room.
• Metric II — Reach: the number of floors on which a possibility remains citable.
• Metric III — Recurrence: the frequency with which a possibility is re-entered in the register without amendment.
• Metric IV — Withheld Weight: the pressure a possibility exerts on a shelf that it does not yet occupy.
• Metric V — Yield: the number of Pending Resolutions a possibility is expected to discharge.
• Metric VI — Opacity: the degree to which a possibility resists description in fewer than nine words.
• Metric VII — Retention: the period, in Ardors, for which a possibility may be held in a Passive Holding before the Manual requires its review.

Metric IV has no upper bound and is measured with a floor-plate of the standard dimensions fixed by Ambiguous Metrics, Annex 7. Metric VI is the only Metric that may be reported as a fraction; the School resists reducing it further, and a proposal to round Opacity to the nearest whole number was struck down by the Twenty-Second Concordance on the ground that "no authority may be derived from potentiality alone" (Twenty-Second Concordance, §9).

Origins and the Eleven Recensions

The original schedule comprised four Metrics, the remaining three having been added in the Year of the Script 203 to accommodate the volume of returns arriving from the Bureau of Arrival Metrics. The first recension, in 191, is the shortest on record: it corrected the spelling of Metric III throughout and nothing else. The fourth recension (Clerk-Adjutant Moven, 214) deleted Metric IV entirely and was reversed within the year when it was found that the deleted Metric continued to be reported on every form in circulation. The School has since treated the fourth recension as never having occurred, though it survives in the bound registers of the Western stacks and is cited, awkwardly, by anyone who consults them.

Recensions five through nine were procedural. The tenth, in the Year of the Script 287, added the requirement that all seven Metrics be entered on a single sheet; the eleventh, in 311, permitted staples. Both remain in force.

Dispute: Ordinal versus Aggregate Reporting

The chief scholarly disagreement concerns whether the seven Metrics are to be read as an ordinal sequence, each presupposing the last, or as independent aggregates to be summed. The School of Perpetual Potentiality holds the ordinal reading, and its Commentary on Annex 2 argues that "the Metrics ascend as the Tower ascends, and no floor reports Metric V before it has reported Metric II" (Commentary, folio 44r). The Office of Unresolved Metrics dissents. In its Observations on Floor 201, it notes that the annex nowhere states an order of precedence and that its own returns have for forty years entered Metric VI first, "since Opacity is the only Metric that may be settled on sight" (Observations, §17).

The dispute was sharpened by the Great Survey of Spiral 89–94, for which the School was a joint initiator. The Survey's conclusion, Conclusion 992, treated all seven Metrics as aggregate and reported a combined figure for the spiral that the School has since called a prophetic outlier. The Department of Ambient Metrics has declined to comment, referring inquiries to the Bureau of Abstract Metrics.

"Where the Metrics disagree, the sheet is not in error; the possibility is."

— Sixteenth Concordance, Annex 2, §11

Application and Incident

In practice the Metrics are completed on the long form, in order, at the desk on the floor of registration. The exercise is not without hazard. During the Great Stillness of Scribe-Primus Elara in the Year of the Script 211, when libration metrics in the Western Salt-Corridor fell to zero for seven days, every possibility registered in the Corridor returned a Metric II of zero, and the aggregate returns from Spiral 89 were accordingly reported as wholly latent for the quarter. The School has never fully corrected the record; the errata slip, filed in 213, is itself listed as pending.

Metric IV is not to be measured on a floor where a floor-plate is already in use, and the plate must be removed before the lights are extinguished. A petition of infinite regress was admitted in 268 by a clerk who had entered Metric V before Metric II in a single filing; the petition was heard, dismissed, and reused as a precedent on nine subsequent occasions, which the Seven Refutations of the Unyielding Lemma describes as "the Tower's most economical ruling" (Refutation 5).

The current master register occupies forty-one shelves on Floor 201 and is closed to consultation on the first working day of each month, when the Ardors are re-seated.