Blank and merged cells

Avoiding blank cells

Tables with merged cells are generally not accessible because a screen reader might not be able to determine the reading order for the merged cells. However, sometimes merged cells are needed to make the information more readable for audiences who do not use a screen reader. In such cases, you will need to find a compromise between accessibility for users with special needs and clarity for others.

Avoiding merged cells

Tables with merged cells can be made accessible in HTML or PDF by tagging each cell (e.g. with ‘colspan’, ‘rowspan’ and ‘id’ tags) to ensure the correct reading order. Using HTML or PDF is the best solution for making tables with merged cells accessible.

There are several strategies for making complex Microsoft Word tables accessible. 

Use merged cells only in header rows

Screen readers can generally handle merged cells in header rows. Cells can be merged horizontally to give an overarching heading for several columns, or vertically to avoid blank cells:

Do not use spanned rows for subheadings

Tables should not contain spanned subheading rows – many screen readers cannot deal with this structure. In the example of a poorly structured table, the title is in the first row of the table, the body of the table has spanned subheading rows, and multiple data categories are combined into 1 column:

Instead, restructure the table. Subheadings can usually be moved to a new column, usually the first column of the table. This may create a vertically merged cell, but this is generally acceptable in the left (first) column of the body of the table – the screen reader should read the merged cell as a row heading each time it returns to the left of the table:

An alternative approach is to repeat the information from the original subheading instead of vertically merging cells. So the 2 left-hand columns from the example above become 1 column, with entries Professional classification – doctor, Professional classification – nurse, and so on:

Split a complex table into several simpler tables

One way of avoiding merged cells is to split the table into several simpler tables that do not have merged cells.

In particular, if there are several subheadings or major shifts in the nature of the subheadings, the table may be better split into several tables, turning the subheadings into the table titles: