Namespaces
can be both simple and complicated. The very first example schema in
this book included an attribute from the xml:lang
namespace and it didn’t seem like a big deal.
However, if you think about it more carefully,
you’ll see that namespaces present two different
challenges to schema languages. The first is that schema languages
need to provide a way to specify which namespaces apply to the
elements and attributes that are described; the second is how to cope
with extensibility, one of the objectives of XML
namespaces.
In this chapter, we’ll take a closer look at these two challenges and how RELAX NG addresses them.
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