LexEOS content is kept in a source file in XML format. A transformation system generates the HTML that the learner uses.

The LexEOS author has two tasks: firstly, the creation or collection of 'assets' (such as images and texts) for the page and secondly, editing a LexEOS data file using an XML editor of choice. All the 'back office' processing is done by the LexEOS system.

Authoring in LexEOS is a process of editing the XML source file using one of the many validating XML editors now available (a number of them are freeware).

LexEOS does not require a custom-built, proprietary editing tool. Authors can edit the LexEOS XML source files directly using a simple validating XML editor of their choice.