By Kevin Cheung, Associate Professor, School of Mathematics and Statistics

I find it unfortunate that the word “eBook” is used to refer to a collection of electronic resources on a particular subject. Whenever I hear the word “book”, I can’t help thinking about a physical book. I don’t think I am alone in this regard. Such a mental association with physical books can affect how one approaches writing an eBook.

In the not-so-distant past, publishing a book involved a typesetting step that nails down the various visual aspects of the book (e.g. font size, margins and page layout) for the creation of a camera-ready format, such as PDF, for printing. However, an eBook targeting web browsers or eReaders can only make mild assumptions on the dimensions of the viewing area. Hence, the ability for text to “reflow” is critical. Traditional authoring tools such as Word, Pages, LibreOffice and LaTex that target print are not necessarily the best choices for authoring eBooks responsive to screen dimensions.

In addition to reflow, there are a number of accessibility issues, such as font type and size, colour contrast, and headings, that need to be solved. In fact, there is a set of a11y guidelines that authors are expected to follow. (A11y is a numeronym obtained from “accessibility” by replacing the letters between “a” and “y” with the number of letters to replace, which is 11 in this case.) There are a large number of aspects that authors must be aware of. Fortunately, the work is made easier using a11y checkers, such as the one at WebAIM. Unfortunately, proper handling of math formulas and math expressions is far from straightforward.

Back in the 1990s, math expressions and formulas were mostly bitmap images that often looked jagged and out of alignment with surrounding text. When browsers started supporting SVG (scalable vector graphics), visual quality of math content improved considerably. In any case, once you have an image, you can create descriptive text (called alt text) that provides context of what the image contains. So when a person with a visual impairment comes across an image on a website, their screen reader can read the alt text. As a result, the math content is available to both the sighted and people with visual impairments.

Problem solved? Not so fast. Take a look at the math expression here. This example might look contrived but in real life, one can encounter math expressions that are far more complex. Now, what would the alt text for the equation look like? It probably would be quite long and most people (sighted or with a visual impairment) will need to hear it many times to digest it.

As the saying goes, “A picture is worth a thousand words.” If you are creating a web page or an eBook that contains images, you will need to include the associated words somehow. But humans have limited working memory. Once the description of an image or math formula becomes long, it needs to be broken down into pieces. This brings us to another important issue: explorability. This is when things start to get tricky for e-“books”.