Namespace declarations

- indirection: namespaces are declared by special attributes and associated prefixes

Example:

<... xmlns:foo="http://www.w3.org/TR/xhtml1"> ... <foo:head>...</foo:head> ... </...>

xmlns:prefix="URI" declares a namespace with a prefix and a URI.

Scope of declaration: lexical (the element containing the declaration and all descendants - can be overridden by nested declaration)
Both element and attribute names can be qualified with namespaces.

Note: the prefix is just a proxy - applications should use only the URI.