Accessible PDF conversion with complex tables

Definition I PDF Conversion I Available Settings I Table Settings

Definition

A complex table is one in which the association between header and data cells cannot be easily determined from the layout of the table using simple rules.  The “Other” in the table menu option makes it possible to specify the structure of complex tables and to ensure that they will be read correctly. 

The following table shows the price of apples and oranges in North America and Europe from 2002 to 2006. The data cells in the rows under North America (rows 3 to 8 from the top) have as their header the first and second rows from the top. The data cells in the rows under Europe (rows 10 to 15 from the top) have as their headers the first and ninth rows from the top. The bottom row (row 16) has the top row as its header.

Complex tables such as these can only be supported by specifying Linked Headers which directly link header cells (TH) with associated data cells (TD) at any location in the table. Linked headers allow screen readers and other assistive technology to process the structure of even exceptionally complex tables.

Picture showing a PowerPoint slide containing a complex table where the relationship between headers and data cells does not follow simple rules.

Table headers are not supported in PowerPoint’s interface but are supported in the PDF format. You can define linked headers in CommonLook Office for inclusion in the generated PDF document’s tags.

PDF Conversion

When the above table is converted to PDF, CommonLook Office will tag the column and row headers correctly, including any linked headers.

Available Settings

Generate Speak Text: When checked, this option generates an alternative textual description for each of the table’ s cells. This option provides support for the most basic types of linear screen readers which may not support table header structures.

ADVISORY: Speak Text may have the effect of making the table less useful to users with PDF-friendly assistive technology that can leverage table structures in PDF files. For this reason, it is recommended that Speak Text is generated only if required to support devices or software that do not fully process table structures in PDF.

Table Settings

Clicking on Edit Cells in the CommonLook Office panel at this checkpoint opens a basic table editor to specify the properties of cells and to define linked headers.

Picture showing the Settings window which provides functionality to edit the properties of the cells and to define linked headers .

Cell Types

All cells are defined as Data cells (TD) by default, meaning they contain data as opposed to header information. For simple tables you only need to ensure header cells are defined and scoped.

  1. Select the cells you wish to set as headers.
  2. Right mouse click to display a popup menu.
  3. Click the “Set as Header” option and specify the header type (column, row or row and column).
  4. When finished with all cells in the table, click “Ok” to close the table editor.

Tip: You can select multiple cells using shift-click for contiguous multi-select or control-click is for non-contiguous multi-select.

Tip: If you make a mistake, you can revert a cell type back to Data by selecting the Set as Data option.

Excluded Cells

In some cases, cells are mistakenly embedded into a table. For example, table captions may be inserted as the top or bottom row in a table. To exclude such cells from the table, select the cells you wish to exclude and right-mouse click to display a popup menu. Select the option Exclude from Table.

Linked Headers

Linked headers provide a powerful tool to link headers with data cells no matter where they exist within the table.

Picture showing the Settings window which provides functionality to edit the properties of the cells and to define linked headers .

To associate data cells with one or more header cells using linked headers:

  1. First, ensure all Header cells have been marked as such.
  2. Click on the “Linked Headers” tab in the Settings window.
  3. Select the “Assign Headers” radio button.
  4. Select the header cell from the left pane. CommonLook Office will mark it as H-1.
  5. Select the data cell to be linked to the header cell from the right pane.
  6. Click on the assign headers button.

To view the linked header cells associated with a given data cell:

  1. Click on the “Linked Headers” tab in the Settings window.
  2. Select the “View Headers” radio button.
  3. Select the data cell from the right pane. CommonLook Office will highlight all linked header cells that are associated with it.

Caution: Assigning a linked header cell replaces previous header information from the data cell.

Tip:  Select row headers first and then column headers, from the most specific to the most general.  Multiple headers can be selected by holding the CTRL key while selecting cells.  Multiple data cells may also be selected by holding the CTRL key when clicking.

Tip: If you make a mistake, click Reset and start over. Note that this will reset all defined linked headers for all cells in the table.

Guidelines and Standards

This checkpoint is relevant to the following regulations, guidelines and standards.

DocumentPublishedScopeConformance Criteria
Section 508 (USA)2001“Web-Based Information & Applications”(g) & (h)
W3C WCAG 2.02008Web ContentSC 1.3.1
ISO 14289 (PDF/UA)2012PDF TechnologySection 7.5

 

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