EAN-13

how thirteen digits become 95 modules of bars and spaces

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

The strip above the bars shows how many modules each zone of the symbol takes. The table below reads two ways: on the left, how each digit is drawn in each of the three sets; on the right, which sets the left six run in when that digit stands first in the number.

NO BAR ANYWHERE DRAWS THE FIRST DIGIT

Twelve seven-module characters carry twelve digits, and the number has thirteen. The first digit is nowhere in the bars: it is carried by which sets the left six are drawn from. In 2950411707433 the first digit is 2, and the pattern LLGGLG is that digit.

Put 3 in its place and the drawn characters stay the same digits — only the sets they are taken from change (LLGGGL). This is why the digit is printed on its own to the left of the bars: the scanner reads it, the eye does not.

On the sheet

The strip above the bars shows how many modules each zone of the symbol takes. The table below reads two ways: on the left, how each digit is drawn in each of the three sets; on the right, which sets the left six run in when that digit stands first in the number.
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 7 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.

EAN-13

NO BAR ANYWHERE DRAWS THE FIRST DIGIT

On the sheet

Printing

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