Effective XML: 50 Specific Ways to Improve Your XML

Undeclaring Namespace Prefixes

There's one other new feature that's effectively part of XML 1.1: namespaces 1.1, which adds the ability to undeclare namespace prefix mappings. For example, consider the following API element.

<?xml version="1.0" encoding="UTF-8">
<API xmlns:public="http://www.example.com"
      xmlns:private="http://www.example.org" >
  <title>Geometry</title>
  <cpp xmlns:public="" xmlns:private="">
    class CRectangle {
      int x, y;
      public:void set_values (int,int);
      private:int area (void); }
  </cpp>
</API>

A system that was looking for qualified names in element content might accidentally confuse the public:void and private:int in the cpp element with qualified names instead of just part of C++ syntax (albeit ugly C++ syntax that no good ...