Irregular table (missing cell)

PAC 2 Warning

Irregular table


Logical Structure: Structure Elements: Tables

Failure Condition

Matterhorn Protocol Checkpoint 15-005: A given cell’s header cannot be unambiguously determined.


This suggestion applies to a table that is intended to be simple and regular (each row has the same number of columns and vice versa), but is irregular due to one or more missing table cells.

In PAC 2, inspect the table using the Screenreader Preview feature to determine the cause of the table irregularity – that is, where do cells need to be added such that each row has the same number of columns and vice versa, and such that the table makes sense when presented through assistive technology. Add table data cells in the Acrobat Pro tags pane as needed to remediate the table.

Example PDF with this error

Video version of this tutorial: