MathML::Entities a content conversion filter for named XHTML+MathML entities. There are over two thousand named entities in the XHTML+MathML DTD. All the Entities defined in the XHTML+MathML DTD except the five "safe" ones (<, >, &, ", '), will be converted to the equivalent numeric character references or to utf-8 characters. Named entities which are not in the XHTML+MathML DTD are escaped. This makes the resulting XHTML (or XHTML+MathML) safe for consumption by non-validating XML parsers. Unlike, HTML::Entities, the mapping between MathML named entities and codepoints is many-to-one. Therefore, there's no particular sense in having an inverse function, which takes codepoints to named entities. Based on: HTML::Entities by Koichi Taniguchi WWW: http://search.cpan.org/dist/MathML-Entities/