XML Programming Language, specification to write

At https://en.wikiversity.org/wiki/XML_Programming_Language

I started to write specification of a Turing-complete macro language for 
XML.

First, it will allow to define macroses without arguments (with use 
similar to XML entities), macroses with arguments, and macroses with 
full-featured programming capabilities.

Please help me to develop the specification and to implement it.