PDF/A-4: the edition built on PDF 2.0
The fourth edition, published in 2020, is the first built on the current version of the PDF format. It simplifies the claim rather than adding to it.
- Published text
ISO 19005-4- Year of the edition
- 2020
- Version it rests on
- PDF 2.0
Summary
Three things changed. The letters after the number are gone: there is one plain claim, and what used to be the middle level — every character mapping back to the letter it stands for — is now asked of every document.
Being readable by software that reads a page aloud became a standard of its own rather than a level of this one. A document that needs both claims both, and says so twice.
And the claim is stated in one place instead of two: the packet that says what the file is. The older, smaller information dictionary that used to repeat it is not written at all.
Technically
The part rests on PDF 2.0, published as ISO 32000-2. The a, b and u letters of the earlier parts are gone; what the letter u of part 2 asked for is required of every document, and what letter a asked for now belongs to the accessibility standard, whose second part is written against the same version of the format.
Two further claims stand beside the plain one, PDF/A-4e and PDF/A-4f. The first is for engineering documents and lets a page carry a three-dimensional model; the second is for a document carrying files of any kind, and asks for at least one.
A document of this part carries no information dictionary at all: the claim, the title and the dates are stated in the description packet and there alone. Through the service the part is asked for as archive with the value pdfa4 or pdfa4f.
Clause by clause
The plain claim and the level for carrying files are both written today, and a request asks for either by name. The engineering level is planned for a future version.
The levels of this part
| Level | What it adds | Asked for over the network as |
|---|---|---|
PDF/A-4 |
The page, and every character drawn mapped back to the letter it stands for. There is no letter after the number: this is the whole claim. |
pdfa4
|
PDF/A-4E |
The same, for an engineering document: a page may carry a three-dimensional model of the thing it describes. | Planned for a future version |
PDF/A-4F |
The same, for a document carrying files of any kind. It asks for at least one. |
pdfa4f
|
What this part asks for
- The document header names PDF 2.0.
- Every character the document draws maps back to the letter it stands for, with no level to opt out of.
- The claim is stated in the description packet, naming the part and the year of the edition.
- At least one carried file, at the level meant for carrying them.
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:
- The older information dictionary: the claim is stated once, and a document that states it twice can state it two different ways.
- A carried file that is not itself archival, unless the claim is the level meant for carrying files.
- A three-dimensional model, unless the claim is the engineering level.
Where this part stands here today
Written today, and asked for by name through the service. The level for carrying files is written by the engine as soon as the document carries one.
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 19005-4 6.1.2 |
The version the file header names is the one the part rests on. |
ISO 19005-4 6.1.3 |
A document of this part says what it is in its description packet and there alone. |
ISO 19005-4 6.2.10.4.1 |
Every font the document draws with is carried inside the file. |
ISO 19005-4 6.2.7.1 |
What reading software is to do between an image's samples is stated, not left to it. |
ISO 19005-4 6.6.1 |
Which kinds of action a document of this part may hold. |
ISO 19005-4 6.9 |
A document at the level for carrying files names the files it carries. |
ISO 19005-4 6.10 |
What a set of layers a reader can switch off has to declare. |