Remarks

The top-level element for math tagged according to the MathML Tag Set.

Changes to MathML: 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+).

MathML Namspacing: The vast majority of users of this Tag Set use the DTDs as their primary (or only) model, so this 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 DTDs, 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.

Some current MathML viewers cannot handle MathML elements that are prefixed (using the tag <mml:msub> rather than the tag <msub>) unless the MathML namespace pseudo-attribute has been placed directly on the <mml:math> element (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"); the presence of the namespace on the top-level element is not good enough. By default in this Tag Set, the namespace has been established as a #FIXED attribute on the <mml:math> element, but processors not using a DTD/schema cannot see defaulted or #FIXED attributes. For such processors, the MathML namespace attribute must be placed directly on all <mml:math> elements in the instance document.