High Quality Content by WIKIPEDIA articles! FleXML is an XML transformation language originally developed by Kristofer Rose. It allows a programmer to specify actions in C programming language or C++, and associate those actions with element definitions in an XML DTD. It is similar in philosophy to Yacc and the Lex programming tool in that it is a syntax-directed driver; one could establish the analogies Yacc:LR(1) grammar::Lex:Regular grammar::FleXML::XML.