Notation and symbols have proved very important for scientific documents, especially in mathematics. Mathematics has grown in part because its notation continually changes toward being succinct and suggestive. There have been many new signs developed for use in mathematical notation, and mathematicians have not held back from making use of many symbols originally introduced elsewhere. The result is that science in general, and particularly mathematics, makes use of a very large collection of symbols. It is difficult to write science fluently if these characters are not available for use. It is difficult to read science if corresponding glyphs are not available for presentation on specific display devices. In the majority of cases it is preferable to store characters directly as Unicode character data or as XML numeric character references. However, in some environments it is more convenient to use the ASCII input mechanism provided by XML entity references. Many entity names are in common use, and this specification aims to provide standard mappings to Unicode for each of these names. It introduces no names that have not already been used in earlier specifications. Specifically, the entity names in the sets starting with the letters "iso" were first standardized in SGML () and updated in , the entity names in the sets with names starting "mml" were first standardized in MathML and those starting with "xhtml" were first standardized in HTML .

This specification defines Unicode mappings of many sets of names that have been defined by earlier specifications.

We first present two tables listing the combined sets, firstly in Unicode order and then in alphabetic order.

Then there come tables documenting each of the entity sets. Each set has a link to the DTD entity declaration for the corresponding entity set, and also a link to an XSLT2 stylesheet that will implement a reverse mapping from characters to entity names (this is, of course, only possible for entity names that map to a single uniocde code point).

In addition to the stylesheets and entity files corresponding to each individual entity set, a combined stylesheet is provided, as well as two combined sets of DTD entity declarations. The first is a small file which includes all the other entity files via parameter entity references; the second is a larger file that directly contains a definition of each entity, with all duplicates removed.

Certain characters are of of particular relevance to scientific document production. The following tables display Unicode ranges containing the characters that are most used in mathematics.