See documentation for the Mathematical Markup Language (MathML) 2.0 DTD.
This alttext attribute is used only within mathematical expressions. The equivalent function, providing a textual word or phrase that can be displayed “behind” a graphic or pronounced over a graphic, is accomplished using the <alt-text> element for graphics (and other elements) in this DTD.
| Value | Meaning |
|---|---|
| Text, numbers, or special characters | See MathML documentation. |
| Restriction: This attribute may be specified if the element is used. | |