Remarks

With one exception, the various elements and attributes of MathML used inside <mml:math> are not documented here, and the reader should refer to online documentation from the W3C and Design Science. The one exception is the <mml_annotation-xml> element. The content model for the <mml_annotation-xml> is normally “ANY”, but this causes difficulties in many editing tools, so this Tag Set has reduced the content model to one or more paragraphs: (p+).

The vast majority of users of this Tag Set use the DTDs as their primary (or only) model, so the Tag Set is maintained to ensure that users of DTDs and DTD-based tools will work well. Because DTDs do not “play well” with namespaces, and most DTD-based tools are not namespace aware, the MathML namespace has been hardcoded to the prefix “mml” in the DTDs. This means that the element name, in the Tag Sets, really is <mml:math>. While this was the usual prefix when this Tag Set was originally established, the more frequently seen prefix is now “m”. Since XSD and RNG use “real” namespaces, this makes no difference to them, as to a namespace-aware processor a namespace prefix is only a placeholder. For DTD users, the element names in the MathML will need to be “mml” (for example, mml:mfrac), but tools can be set to provide that prefix and the essence of namespaces is that prefixes do not matter, so no harm is done.