Table rows, TH and TD, Headers and Regularity – Failed

The Accessibility Checker in Adobe Acrobat Pro has five table rules: Rows, TH and TD, Headers, Regularity and Summary. A result such as Regularity – Failed or Headers – Failed means a table's tags, the hidden structure behind it, don't describe a clean grid of rows, header cells and data cells. When that structure is broken, a screen reader can't announce the table correctly, and values get read under the wrong headings or with no headings at all.

What this means

Acrobat expects every table to follow this structure: a Table tag holds rows (TR), optionally grouped into THead, TBody and TFoot, and each row holds header cells (TH) and data cells (TD). Each rule checks one part of that:

The Summary rule is the odd one out. Adobe's own help says table summaries are optional, although they can improve accessibility. WCAG 2.1 doesn't require them. A one-sentence summary helps with a large or complex table, but a Summary failure on its own doesn't make a table inaccessible.

Passing all five rules still doesn't guarantee a usable table. PDF/UA, the ISO standard for accessible PDFs, also requires each header cell to be linked to its data cells, which Acrobat doesn't check. PAC does, under TH has associated cells.

Why it matters

Screen readers use these tags to say where a person is, such as "row 3, column 2", and to announce the header for each cell as they move. With broken structure, numbers are read under the wrong header, rows run together, or the table is read as a jumble of text. In a budget, fee schedule or election results table, that can change the meaning entirely. This is WCAG 2.1 success criterion 1.3.1, Info and Relationships.

How to fix it in Acrobat Pro

Fix it in the source file

Clean tables in the source produce clean tags:

• Word: use a real table, not tabs or spaces. Turn on Header Row in Table Design, and in Table Properties > Row turn on Repeat as header row at the top of each page. Turn off Allow row to break across pages so a row isn't split. Avoid merged cells, blank rows or columns for spacing, and tables inside tables. Microsoft also documents that some newer Word builds treat a table with no borders or shading as a layout table and tag each cell as a paragraph, so give data tables visible borders or shading.
• InDesign: turn top rows into header rows with Table > Convert Rows > To Header, and avoid merged cells where you can.
• Any app: keep tables simple. One header row and at most one header column is easiest for everyone, including screen reader users.

Fix it automatically with Includoc

Includoc rebuilds table tags automatically as Table, TR, TH and TD, and fixes simple irregular tables, such as rows with missing cells. Deciding which cells are headers takes judgment, so our AI identifies header rows and columns and you confirm them in the tables panel on the review screen.

Complex tables, such as those with merged cells or several header rows, are flagged for review with suggested headers rather than changed silently. If a complex table matters, such as a budget people rely on, the human-verified tier checks it for you.

Standards

Related errors

• TH has associated cells: PAC's stricter check that header cells are linked to their data cells.
• List items and Lbl and LBody – Failed: the same kind of structure problem, for lists.

For a complete walkthrough, read Tables in PDFs, or check a PDF free to see which tables need work.