The program texvc (TeX validator and converter) validates (AMS) LaTeX mathematical expressions and converts them to HTML, MathML, or PNG graphics. It was written by Tomasz Wegrzanowski and was integrated into MediaWiki. Since early 2012 WikiMedia projects use it only to show mathematical expressions in PNG, which is the default option.
The <math> tag of MediaWiki's wiki code is used for mathematical formulas and similar content. It may be rendered either on the server side (with Math extension which uses texvc) or on the client side (for example, with MathJax). The aim is to allow a single syntax for math markup while providing protection against potential security issues. In addition, texvc provides some extensions to standard AMSLaTeX, such as
\codes for HTML math character entities (for example,
\Sigma) which have different names in LaTeX.
Texvc is written in OCaml, along with PHP code to integrate it with the rest of MediaWiki. It uses dvipng (instead of the commonly used combination of ImageMagick and dvips) to convert LaTeX's output to PNG files. Like the rest of MediaWiki, it is available under the terms of the GNU GPL from the MediaWiki site.