For several decades TEX and LaTEX have been the de facto standards for authoring mathematical and technical documents. However, as the Web is increasingly important for all kind of purposes, including scientific communication and education, new forms of mathematical markup are gaining importance. Indeed, MathML, both presentation and content, and OpenMath are relatively new markup languages for mathematical expressions that get more and more attention. These new standards offer new posiblities. In particular, the semanticaly rich presentation of mathematics with content MathML and OpenMath make it possible to easily connect to mathematical services, like computer algebra systems, or to translate the mathematics to other formats. However, putting mathematical expressions and documents on the Web is still difficult.

In the past decade, several companies and research institutes have developed mathematical expression/formula editors. These editors usually aim to describe the visual appearance. The Amaya, LyX, TeXmacs and MathType editors are using MathML Presentation, LaTEX, or native formats to store expressions for describing the expression appearance. Only a few formula editors like MathEX, Sentido and Wiris use MathML Content or OpenMath to capture the meaning of expressions.

These editors can often be integrated as a plugin with Web-based (X)HTML editors, like FCKeditor or tinyMCE, that run in a browser. Usually these editors are then opened in a seperate window or frame and the user has to create a formula inside this seperate window and paste it in to the document. We propose to create a new Web-based tool, called MathDox Editor, for the interactive entering and editing of semantically rich mathematical documents and expressions, featuring:

• rich mathematical document structure (theorem, lemma, proof etc)
• inline editing of mathematical formulas
• semantic presentation of mathematics in OpenMath
• basic output format MathDox (an extension of DocBook and OpenMath)
• various output formats through XSL-transformation: XHTML-MathML 2.0 and 3.0, ODF-MathML, LaTEX
• access to computational back engines (e.g. Computer Algebra Systems, like Mathematica, Maple and Maxima, GAP, or other OpenMath enabled mathematical software)

This online editor is envisioned to be used inside (mathematical) e-learning tools, such as Learning management systems, forums, assessment systems etc, but also for writing short notes and mathematical webpages. At a later stage, one might extend the system to a fully featured mathematical text editor.