aqui he usado lenguajes mixtos con XML namespaces. Que es?
<?xml version="1.0">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:m="http://www.w3.org/1998/Math/MathML">
<head><title>holà</title></head><body>
<m:math>
<m:mi>x</m:mi> <m:mo>=</m:mo> <m:mn>2</m:mn>
</m:math>
