Documents that will still open decades from now, that a screen reader can read aloud, and that an accounting system can book without anyone retyping them.
Some documents have to outlive the software that made them. An archival PDF carries everything it needs inside it — the fonts, what its colours mean, a description of itself — so that nothing it depends on can go missing later. Public bodies and long-term archives ask for exactly that, and there are programs that check it.
The same care is what makes a document readable by somebody who cannot see it. The file can carry its own structure — this is a heading, this is a table, this is the wording that stands for a picture — so a screen reader announces the page in a sensible order rather than in the order the marks were drawn.
Three rulers — centimetres, inches and points — on a page that tells whatever prints it to put it out at exactly the size it was drawn, and to offer nothing else. Lay a tape measure on the printed sheet and you can check for yourself.
Two sittings bound into one file. Each page carries a record of its own — what it is, whose hand wrote it, the day it was written — the photograph on the second page carries one too, and each transcription is tied to the page it transcribes rather than to the file at large.
A records office's reference, the department it came from, the date until which the document must be kept and its classification, carried inside a file an archive still accepts. No archiving rule knows what a keep-until date is, so each entry carries a description of itself, and that description is what makes a checker accept a fact you alone invented.
Every line of the note carries the order it was picked for, the article code and the shelf it came off, and prints none of them. The place where the driver signs carries the round and the van, and one beside the fold tick carries nothing but its own place.
Two pages carrying a copy of themselves that nobody sees: this is a heading, this is a table, and this is the order to read them in. Software reading the document aloud follows that instead of the order the marks were drawn in, and skips the running head. On the page, nothing looks any different.
A parts list whose first column is a picture rather than a word. Each picture carries the sentence somebody hears in its place, so nothing in the list is lost on a reader who cannot see it. On the page, the pictures are simply pictures.
The electronic invoice French law has required since September 2026: one file, a page a person reads and the same invoice inside it as XML. Nothing to reconcile afterwards, because there is only ever one invoice.
The library reads the invoice as it stands and names, clause by clause, everything between it and Factur-X. Two things stand in the way, then one, then none — and only then is a file written.