PAC 2024 – Header cell without assigned subcells

PAC 2024 error details

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category

Logical Structure > Structure Elements > Tables > Assignment of Header Cells

Error message

Header cell without assigned subcells

Matterhorn error condition

15-003 (In a table whose cell assignments are not controlled using header attributes and IDs, TH cells without a scope attribute exist.)

explanation

There is a table cell in the document that has been tagged as a table header cell (TH). However, it has not been defined which table data cells are subordinate to this table header cell. This can mean that you still have to rely on the visual form of the document when capturing the table structure, since various auxiliary tools (eg screen readers) can only evaluate the structure with correct relationships between header cells and content cells.

solution in Adobe Acrobat Pro

solution approach

To correct the error, at least one table data cell must be subordinated to each table header cell. If the table has a simple structure (e.g. each row contains the same number of cells), the table header cell can simply be assigned the scope (e.g. "column"). This means that all table data cells that are in the scope of the table header cell are subordinated to it. However, if the table has an inconsistent structure, a unique ID must be created for each table header cell, which is then assigned to each relevant table data cell.

video tutorial

picture instructions

1. In the search bar, search for the “Reading Order” tool and open it

2. Right-click the number at the top left of the table (while the “Reading Order” window is open) >
Open “Table Editor”

3. Right-click the first table heading cell (TH) >
Click “Table Cell Properties…”

4. Select the circumference direction (in the “Circumference” dropdown) >
click "OK"

Note: In the current example, a table cell from the top row is edited, which is therefore a header cell for the entire column. This sets the scope to "Column".

5. Proceed in the same way with all other table heading cells

If you are editing a table with an irregular structure (very rare), you usually cannot use the scope function. In this case, skip steps 3-5 and continue with the following steps instead.

6. Remove the table header tag from all cells that are not table header cells (declare them as data cells instead)

7. Right-click table >
Click "Automatically generate heading cell IDs"

Note: Each table header cell now has a unique header cell ID that begins with R[X]C[Y], where [X] indicates the row number (R = row) of the cells and [Y] the column number (C = column). For example, the header cell ID "R2C1..." stands for the cell in the second row and first column.

8. Right-click the first table data cell (TD) >
Click “Table Cell Properties…”

9. Click the plus sign >
Select heading cell ID (several if necessary)

Note: In this example, the table data cell in the second row, second column (R2C2) is assigned the header cells. Both the cell in the first row, second column (R1C2) and the cell in the second row, first column (R2C1) are header cells of the data cell. Therefore, both header cell IDs must be assigned.

As soon as you save the document and check it again with the PDF Accessibility Checker, the error message Header cell without assigned subcells disappeared.

When saving, make sure to give the document a new name (e.g. Document Title_Rev2) and not oversave the previous version of the document. This way, you can go back to the previous version of the document if something goes wrong.

Tips for Error Prevention

When creating tables, make sure that the structure is as simple and consistent as possible so that you can use the scope function and do not have to edit each table cell individually. If you create your document in Microsoft Word, also use the table format options (header row, first column) so that the relevant cells are tagged as table heading cells (TH) directly when exporting to PDF from Word.