Character glyphs

(Excerpt from "The MathML Handbook" by Pavi Sandhu)

A MathML expression can contain any character included in the Unicode character set. In particular, technical symbols and other extended characters can be included either using a named entity reference defined in the MathML DTD or, more generally, using the numeric character entity reference defined in Unicode.

However, in special cases, you might need to use a character that is not available in Unicode. Alternatively, you might wish to use a Unicode character but represent it using a variant of the standard glyph associated with the character. MathML provides the mglyph element specifically for use in such situations. It allows you insert a particular glyph from a particular font family at any place in your document.

The mglyph element accepts the following three attributes:

• fontfamily: specifies the font family that contains the glyph.
• index: is a number that specifies the position of the glyph in a particular font family.
• alt: provides an alternate name for the glyph. This name can be used by an audio renderer or by a visual renderer if it cannot find the specified font family for rendering the glyph. If using this, you should choose a descriptive name for it.

These are all required attributes; that is, they do not have a default value and must be explicitly specified in every mglyph element.

Here is an example that shows the use of the mglyph element:

This explicitly specifies that the characters in positions R, A, and B from the Mathematica 6 font family should be used to display certain capital letters in a Gothic script.