XML stands for eXensible Markup Language. YAXX is an XML extension to YACC, which stands for 'Yet Another Compiler-Compiler'. This extension allows a program in a YACC grammar (LALR) to be automatically converted into an XML document that encodes the syntax tree of the program. Moreover, the generated XML document can be validated by a generated DTD (Document Type Description) document. The resulting syntax tree in XML can also be transformed back into the original program through a very simple XSLT stylesheet. The implementation of YAXX is based on an extension to Bison, a public-domain implementation of YACC. The software collects a number of YACC grammars and reference parsers to support the parsing of all major programming languages, including ANSI C, Fortran 77, GNU C++, Java, C#, Ada 95, PHP5, XML, SQL, etc. The original hosting site of the project in SourceForge is still functioning for the release of the tarballs. Developers are encouraged to switch to the new repository hosted here.