Although a benefit of native MathML support in XHTML content documents is the ability to provide voicing based on the markup, reading systems capable of such voicings are rare. It is consequently advisable to include a fallback description.
A description can be added using the
aria-label attribute. The MathML
attribute is not recommended, as it has little support in assistive technologies.
Although natural language descriptions of math equations are a possibility, it is recommended to use MathSpeak to write descriptions. Readers already familiar with math-voicing programs will recognize the conventions used in MathSpeak, and the language removes the potential for ambiguity that natural language can introduce.
The EPUB Samples Project contains the following publications that include MathML:
Consider the simple equation presented in Example 1 above. A reasonable natural language description might be "the square root of a over b". But consider that there are two ways that this statement could be interpreted:
A reader who cannot see the visual presentation of the equation is not going to be able to determine which is the correct interpretation with only the description to go by. MathSpeak takes the ambiguity out of the equation by clearly breaking down the components of the equation in a way that doesn't leave ambiguity.
No, but it is the most openly documented format. Although some MathML applications take slightly different approaches to voicing equations, MathSpeak is a good reflection of the typical grammar.
The different levels reflect the expected age and proficiency of the reader. A math book geared towards younger readers, or readers new to the topic, would typically employ the verbose grammar. More advanced readers already proficient in math and familiar with the grammar will likely find the verbose syntax a nuisance, so either the brief or super-brief grammars can be employed.