UM identifier

1. What it is for

Every record in the archive receives a permanent identifier when it is created. It is a short string that never changes, is never reassigned, and finds that record even after the web address used to publish it no longer exists.

The identifier does not replace the readable address: it stands beside it. UM means Universal Memory, the system by which Biography Library counts years from 2026 of the Gregorian calendar, taken as Year 0 UM. The letters UM are part of the string and are not translated.

2. For a reader in the future

The string is a name. It does not describe the person and holds no information about them. It always starts with UM, then the year of creation counted from a year zero, then twelve characters of which the last is a check character. The calculation can be done by hand.

The body uses twenty-nine characters: ten digits and nineteen letters. Vowels are left out so the string cannot form words. Letters that are easily confused with digits are left out too.

3. Canonical form

Example: UM-0000-K3NQ-7FX2-MVP4. Four parts separated by hyphens. UM is the scheme name. 0000 is the UM year, written with at least four digits. Year 0 UM is Gregorian 2026; each UM year begins on 1 January, in Coordinated Universal Time. Past year 9999 the year field grows. The last twelve characters are eleven assigned characters and one check character, always last. The written form uses capitals.

4. Alphabet

The body uses only these characters, in this order, with values from 0 to 28:

0 1 2 3 4 5 6 7 8 9 B C D F G H J K M N P Q R S T V W X Z

The vowels A, E, I, O, U and the letter L are excluded. The year field uses only the digits 0 to 9.

5. Comparison and normalisation

Two identifiers are the same if they match after hyphens and spaces are removed and a single letter case is used. UM-0000-K3NQ-7FX2-MVP4, UM0000K3NQ7FX2MVP4, and um-0000-k3nq-7fx2-mvp4 are the same identifier. A system that accepts them must accept all of these forms.

6. The check character

The last character is calculated from all year digits and the eleven body characters, without the letters UM and without the hyphens. Positions are numbered from one. Each character becomes its alphabet value, is multiplied by its position, the products are added, the sum is divided by 29, and the remainder is kept. The check character is the alphabet character at that remainder.

29 is prime: the check always detects a single-character substitution and a swap of two adjacent characters. For UM-0000-K3NQ-7FX2-MVP4 the sum of the products is 1802 and the remainder of division by 29 is 4, so the last character is 4. If the year has more than four digits, positions still start at the first digit.

7. Test vectors

Any implementation must produce exactly these identifiers. The five-digit year vectors exist so that a program which assumes four digits fails on the day it is written, not ten thousand years later.

8. Issuance rules

The identifier is assigned when the record is created and is never changed, nor reassigned, even if the record is deleted. The eleven-character body is random and contains no name, dates, place, or sequence number. Uniqueness is guaranteed by the register: before assignment the system checks that the identifier does not already exist.

9. Resolution

The canonical address is https://id.biographylibrary.org/ followed by the identifier, with or without hyphens and in any letter case. An issued identifier answers forever. If the record cannot be read, the page says that the identifier exists and that the content is not available. It never answers as a missing page. The domain may change; the string is the identifier.

https://id.biographylibrary.org/UM-0000-K3NQ-7FX2-MVP4

10. The issuing authority

UM identifiers are issued only by Associazione Biography Library, Lugano, Canton Ticino, Switzerland, commercial register CHE-416.014.530. No one else may issue strings that begin with UM- under this specification. The association keeps resolution working, publishes this specification, and deposits a copy in the archive.

11. Version of the specification

This is version 1.0. Later versions may add rules but cannot invalidate identifiers already issued. The format, the alphabet, and the check algorithm are final for every identifier that begins with UM-.

12. If Biography Library ceased to exist

The statutes provide that, on dissolution, the archive is entrusted to a custodian and the code stays public. The custodian takes over the duty to resolve issued identifiers. If no custodian takes over, the identifiers remain readable because everything needed to interpret them is in this document.

13. Where this specification lives

It is published on the site, deposited in the public code repository, included in complete archive exports, and copied onto long-term storage together with the biographies.

14. Reference implementation

The reference code, which calculates the check character, normalises the string, and checks the vectors on this page, is in the public repository. This page does not change the alphabet, the check character, the vectors, or identifiers already issued.