Returns the namespace URI of the extended name of the given nodeIf given argument is a node, the function returns the URI string of the namespace specified in the name of node. If the argument is node-set, first node of the node-set will be considered. Empty string is returned if the argument is an empty node-set, a node without name or if the argument is not a node. If the argument is omitted, context node is used instead as if it is a node-set of one element.
Returns the namespace URI of the extended name of the given nodeIf given argument is a node, the function returns the URI string of the
namespace specified in the name of node.
If the argument is node-set, first node of the node-set will be considered.
Empty string is returned if the argument is an empty node-set, a node without
name or if the argument is not a node.
If the argument is omitted, context node is used instead as if it is a node-set of one element.