PDF/A-2: the edition that caught up with the format
The second edition, published in 2011, holds to the same rule as the first and lets a document use what the format had gained in the six years between them.
- Published text
ISO 19005-2- Year of the edition
- 2011
- Version it rests on
- PDF 1.7
Summary
The first edition was written against a version of the PDF format that was already six years behind by the time documents were being written this way in earnest. Anything the format had learned since — see-through paint, layers a reader can switch off, a newer way of storing photographs — was shut out, not because it threatened that rule but because the text predated it.
So a second edition was published that lets those in, with rules around each of them, and adds a third level between the two the first edition offered.
It also lets a document carry another file inside it, on one condition: that carried file has itself to be archival. That is enough for a set of documents kept as one; it is not enough for an invoice carrying its own figures as a data file, which is what the third edition was written for.
Technically
The part rests on PDF 1.7, the version published as ISO 32000-1. Transparency, optional content and JPEG 2000 images become allowed, each under its own rules, and a signature may be written in the form the European rules for signatures describe.
Three levels. Level B and level A are what the first edition offered. Level U is new and sits between them: every drawn character maps back to Unicode, so the text can be searched and copied, without the structure tree level A asks for.
A carried file is allowed where that file is itself a document claiming this family. The relationship between the carried file and the page carrying it is stated, so reading software knows what it is looking at rather than guessing from the file name.
Clause by clause
The engine writes the three levels of this edition, and it writes the third edition as well, which is this one with a single door opened wider: a carried file may be of any kind rather than archival alone. Through the service a request names each of the three levels of this edition by its own name.
A requirement naming this edition is therefore met by the file the engine writes, and a requirement naming the third is met by it too, the two texts being the same text bar that one clause. Which of them an archive names decides only which claim the document makes.
The levels of this part
| Level | What it adds | Asked for over the network as |
|---|---|---|
PDF/A-2A |
The page, its text mapped back to Unicode, and the structure of the document on top. |
pdfa2a
|
PDF/A-2B |
The page alone, as in the first edition. |
pdfa2b
|
PDF/A-2U |
The page, and every character drawn mapped back to the letter it stands for, so the text can be searched and copied. |
pdfa2u
|
What this part asks for
- Everything the first edition asks for, unchanged.
- Every character drawn maps back to Unicode, at level U and at level A.
- A carried file is itself a document of this family, and the relationship it has to the page carrying it is stated.
- A layer a reader can switch off is named and given a state it starts in.
What this part rules out
What every part of the standard rules out
On top of what every part of the standard rules out, this part closes:
- A carried file of any other kind: a spreadsheet, an image or an invoice's data file needs the third edition.
Where this part stands here today
The engine writes the three levels of this edition today, and a request asks for each of them by its own name through the service.
What an archival document written here carries is the same whichever part is claimed — the fonts, the output intent, the description packet, the report and the two independent checkers — and it is set out once, on the page that presents the standard. What every archival document here carries
The requirements, family by family
The requirements group into eight families, the same eight for every part, and each of their pages says what we write for you automatically and the little that is left for you to state. The eight families, and the page each one has
The published texts behind these rules
| Published text | What it asks for |
|---|---|
ISO 19005-2 6.1.2 |
The file header names the version the part rests on. |
ISO 19005-2 6.2.8.3 |
A picture stored the newer way is permitted, and says how many colour channels it holds. |
ISO 19005-2 6.2.11.4.1 |
Every font the document draws with is carried inside the file. |
ISO 19005-2 6.5.1 |
Which kinds of action a document of this part may hold. |
ISO 19005-2 6.6.4 |
The part and the level are stated in the document's own description. |
ISO 19005-2 6.8 |
A carried file names itself in both forms, and is itself a document of this family. |
ISO 19005-2 6.9 |
What a set of layers a reader can switch off has to declare. |