If your accessible PDF is to contain tables, you should think about the table structure early on. The more complex the table structure, the more difficult it will be to set up the tables correctly for accessibility later on. It is also extremely difficult for screen reader users to perceive complex table structures purely auditorily. A table structure that you can perceive with your eyes must be perceived purely auditorily by impaired people. If your table has several heading levels and these headings each apply to different numbers of columns, then this represents an extreme cognitive challenge. Therefore, try to keep the number of columns and rows constant across the entire table. Below we look at three different types of tables and how they can be made accessible.
tables with regular structure
The table with regular structure is the simplest form of table, can be easily converted into an accessible format and is the easiest to understand cognitively by people with disabilities.
1. In the tab “Display” > “Show/Hide” > “Navigation Pane” > “Order” activate
2. In the “Order” window, open “Options” > select “Show Reading Order Window”
3. While the reading order window is open: Right-click on the number next to the table > Open “Table Editor”
4. Select all column header cells (hold down the Shift key to select multiple cells) > Right-click on a column header cell > “Table cell properties…”
5. Select type “Heading cell” and scope “Column” > “OK”
6. Proceed in the same way for row header cells and select “Row” as the scope
7. Make sure that all other cells are declared as data cells
Tables with irregular structure (merged cells)
Tables with connected cells are also relatively easy to perceive by those affected and the conversion into an accessible table is almost no more complex than with a regular table structure
1. – 7. see section Tables with regular structure
8. Select merged cell > Right-click on a column header cell > “Table cell properties…”
9. Set the scope of the merged cell using “Row range” and “Column range” > “OK”
Note: In the example shown, the merged cell spans two columns and one row, so we enter the number 2 for “Column range” and the number 1 for “Row range”.
Tables with irregular structure (multiple heading levels)
For more complex tables, so-called cell IDs must sometimes be used. If the use of the "scope" property is no longer possible for certain areas, then all header cells in this area are given an ID. All data cells assigned to these header cells must then have the relevant header cell IDs entered. Since this implementation is extremely complex, especially for long tables, you should avoid complex table structures if possible.
In the example below, we again use the “Scope” property for the rows. We now use IDs for the columns.
1. – 7. For all regular table areas, proceed in the same way as in the section Tables with regular structure. In this example, this applies to all row header cells.
8. Assign header cell IDs for all irregular table areas: Right-click on one of these header cells > “Table cell properties…”
9. Enter ID (any entry) > “OK” > proceed in the same way for all other irregular header cells
10. Right-click on the first data cell that is within the irregular area > select “Table cell properties…”
11. Make sure that the type is set to “Data cell” > use the green “+” button to add the corresponding heading cell IDs > do the same for all other data cells
Note: In this example, the selected table data cell has two associated header columns (“First Column Header Cell” and “First Second Level Column Header Cell”). Therefore, the IDs of both cells should be assigned.
