UUID

thirty-six characters: where the version sits, where the variant sits, and what each of the eight versions is made of

Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.

Three sizes in one archive — from a sheet on the fridge to a poster on the wall.

Formats: A4 · A3 · A2
What you get: Print-ready PDFs, one per size, with every letterform converted to outlines — nothing to install, nothing to shift.
Subject: code · reference · study

Read left to right: the first digit of the third group is the version, the first digit of the fourth is the variant. The table in the middle says what each version is made of; the strip at the foot shows which values of the seventeenth character belong to this standard and which to older ones.

NOT EVERY BIT OF A VERSION 4 IS RANDOM

Of the 128 bits in a version 4 identifier, 122 are random rather than 128: 4 bits go to the version number and 2 to the variant. That is the price of being able to see what kind of identifier this is without asking anybody.

Six bits sound like a rounding error, and they are: for the chance of a single collision to reach one half you would have to hold about 2.7 × 10¹⁸ of them. The danger is not the size of the space but the source of randomness: 122 bits from a poor generator are worth far less than the six spent on labelling.

On the sheet

Read left to right: the first digit of the third group is the version, the first digit of the fourth is the variant. The table in the middle says what each version is made of; the strip at the foot shows which values of the seventeenth character belong to this standard and which to older ones.
Colour carries meaning, but meaning never rests on colour alone — the sheet reads in black and white.
Nothing about how it was made: the sheet carries only what the reader needs.

Printing

Three sizes in the archive: A4 — 210×297 mm, A3 — 297×420 mm, A2 — 420×594 mm.
All text is converted to outlines. No fonts to install, and nothing shifts on another machine.
White background and sparing fills — it prints on a home printer without draining the cartridge.
Margins of at least 10 mm: a home printer cannot print to the edge.
No stroke thinner than 0.3 mm, so nothing disappears in print.

Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 9 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.

UUID

NOT EVERY BIT OF A VERSION 4 IS RANDOM

On the sheet

Printing

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