PDFcheck✓

Tagged

This check indicates that tags are present in the document. If no tags are present, the file is absolutely not 508 compliant. This check doesn't determine if existing tags are correct.

Possible values:

Tagged Yes (# tags)

Tagged No

Language

All documents should have the language attribute set. Correct values for English documents are (en) or (en-US).

To set the language in Acrobat Pro DC, go to:
File > Properties > Advanced tab > Reading Options > Language drop down

Possible values:

Language (Language abbreviation)

Language Not set

Marked

In the official ISO PDF-1.7 specification [PDF - 9 MB], on page 574:

A Tagged PDF document shall also contain a mark information dictionary (see Table 321) with a value of true for the Marked entry.

Check out more info about Marked on Stack Overflow.

Possible values:

Marked True

Marked False

Marked No

PDF/UA identifier

This checkpoint isn’t a deal breaker. From taggedpdf.com:

The PDF/UA ID attests that the PDF is ISO 14289 (PDF/UA) compliant. It should be added as the final remediation step; otherwise you would kind of be fibbing.

Watch a screencast showing how to fix this issue using Adobe Acrobat Pro DC.

Possible values:

PDF/UA identifier Yes

PDF/UA identifier Not set

Document Title

A compliant PDF will have a readable title specified in File > Properties.

Possible values:

Document Title Document title

Document Title Empty

Document Title Not set