A records office's reference, the department it came from, the date until which the document must be kept and its classification, in a PDF/A-3 file. No standard knows what a retention date is, so each field arrives with a description of itself — its type, who it is written for, what it means — which is what makes a checker accept information you invented. The page prints the same list, so what a person reads and what a machine reads cannot drift apart.
PDF/A accepts metadata no standard ever heard of, but not silently. A piece of information from outside the standards has to travel with a description of itself — what it is called, how it is to be read, who it is written for and what it means — or the file is not conformant.
Here a records office writes down its reference, the department it came from, a retention date and a classification, and the library writes both halves: the metadata itself, and its description beside it. The page prints the same fields, from one and the same list, so what a person reads and what a machine reads cannot drift apart.
The same document is written twice, once in each language. Both files are shown in full, with the code coloured on the server, and can be copied in one click.
The same document is written in each of these languages. Open the one you want to look at.
| Before | 122,159 bytes |
|---|---|
| Now | 51,905 bytes |
| Saved | 57.5 % |
Not one mark on the page changed. See every document measured.
Three rules — centimetres, inches and points — on a page that states it must print at exactly the size it was drawn, and that the reader is to offer nothing else. That second request only exists from PDF 2.0 on, so the file declares 2.0 rather than changing version without you knowing.
Two sittings bound into one file. Each page carries a record of its own — what it is, whose hand wrote it, when — 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. Tying an attached file to anything but the whole document only exists from PDF 2.0 on, so the file declares 2.0.
A document that says what each run of ink stands for, and which runs are only trimmings. Its text and its table describe themselves, a paragraph and a cell at a time. Validates as PDF/A-3a and PDF/UA-1.
A parts list whose first column is a picture rather than a word. Each picture is marked as one and carries the words a reader hears in its place, so nothing in the list is lost on somebody who cannot see it. Validates as PDF/A-3a and PDF/UA-1.
An electronic invoice: a PDF/A-3 file carrying its own XML.
Thirteen slides, each stating the effect it arrives by — all twelve the standard defines — how long that effect takes and how long the slide stands before the next one comes. The file opens full screen, which is the only place a reader reads any of it.