Possibly inappropriate use of a structure element

PAC 2 Warning

Possibly inappropriate use of a [X] structure element

(Note: [X] could be Figure, Form, Formula, or Note)


PDF/UA > Logical Structure > Structure Tree > [X] structure element

Failure Condition

Matterhorn Protocol Checkpoint 01-006: The structure type and attributes of a structure element are not semantically appropriate for the structure element.


This warning could mean various things, but in my experience it usually is due to the Placement attribute. By default Figure, Form, Formula, and Note are inline – as opposed to Block – level elements. For example, a Note tag is frequently nested inside a Paragraph tag. If a Figure, Form, Formula, or Note tag is used as a block level element the Placement attribute should be explicitly set to Block.

In the PAC 2 test report, click the error to see the location of the object in the document. In the Acrobat Pro Tags pane, right click the Figure tag (for example) and select Properties. On the Tag tab of the Object Properties dialog, click the Edit Attribute Objects button. In the Attributes dialog, if there is not a “/Attribute Object #    <<Dictionary>>” item, click the New Item button to create it. Select “/Attribute Object #    <<Dictionary>>” and click the New Item button. In the Add Key and Value dialog, enter Placement in the Key field, and Block in the Value field. Leave Name as the Value Type. Click OK.

An easier approach, if appropriate, could be to create a new Paragraph tag and nest the inline tag inside it.

Example PDF with this warning

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