HTML and CSS Reference
Both should be rendered as the following well-known quadratic formula in browsers that support MathML:
= -± -
In the second case, the prefix associates other elements and attributes with a particular namespace. For example,
the namespace and the prefix are declared on the body element, as shown in Listing 3-60.
Listing 3-60. Namespace and Prefix Declaration on the body
which adds meaning to mathematical notations such as the ones in Listing 3-61.
Listing 3-61. An Example for Using the MathML Prefix
Since MathML is an XML language, it can be directly embedded into XML files, including XHTML (see the next
section). Because of the lack of support for namespaces, MathML embedding was not supported by HTML versions
up to 4.01. HTML5 is the first version of HTML that supports MathML.
Combinations, Profiles, and Mixed-Namespace Documents
Several newly developed web site features are very useful but not required for basic documents. These technologies
are defined by various specifications that can be used as the extensions of certain versions of (X)HTML. One of them
combines markup and additional semantics, while another supports mathematical markup and vector graphics within
(X)HTML documents. Some of these compound documents have their own DTDs they can be validated against and
namespaces 21 that provide containers for the context of identifiers, including uniquely named elements and attributes.
21 By utilizing namespaces, XHTML documents can provide extensibility by including fragments from other XML-based languages
such as SVG and MathML. This option was the privilege of XHTML languages, and was not supported by HTML before HTML5.