The aim of this page is to propose an XML encoding for source code. This is to enable simpler translation between different language source code, code generators and XMI.
The schema aims to be a formal and unambiguous definition of the syntax of xes. It uses the .xsd format which is defined by www.w3.org this site also contains links to tools for working on .xsd files.
I have shown an example of how the schema encodes Java on this page.
Note that the aim of xes is to encode the parsing of source code into a tree structure. This is to define the underling structure of the program and not just to wrap xml tags around the language keywords.