PDF/A-4

PDF/A-4 is ISO 19005-4, and the first part built on PDF 2.0. It reorganizes the conformance scheme rather than just adding features, so it is the part where assuming symmetry with 1 to 3 will mislead you.

There are no A, B and U levels. Plain PDF/A-4 always requires text to be Unicode-mappable, which is what 2U and 3U asked for, and it does not require a tagged structure. Instead of levels there are two optional variants, and UniPDF exposes one profile for each:

The three are not ordered. Where a 2A file satisfies the 2B and 2U checks, a plain PDF/A-4 file satisfies neither the 4E nor the 4F check, because the conformance value is compared for equality. Validating one file against all three profiles therefore always reports a violation of 6.7.3-3 for two of them, which is expected rather than a finding.

In UniPDF the concrete difference between the variants is narrow. 4E permits the SetOCGState and GoTo3DView actions, which the other two profiles strip on apply and report on validate. The embedded file rules that give 4F its name are checked for all three profiles, requiring F, UF and AFRelationship on any file specification with an EF entry.

Part 4 also drops checks the earlier parts carried. There are no implementation limits, no requirement that the document information dictionary agree with the XMP metadata, and no logical structure clause, since there is no A level to need one. The header check is stricter, since a PDF 2.0 header is required.

Where to look

The shared mechanics, the full profile list and the conformance levels are covered on the PDF/A section page.