A node test that is a QName is true if and only if the type of the node (see [5 Data Model]) is the principal node type and has an expanded-name equal to the expanded-name specified by the QName. For example, child::para selects the para element children of the context node; if the context node has no para children, it will select an empty set of nodes. attribute::href selects the href attribute of the context node; if the context node has no href attribute, it will select an empty set of nodes.
A QName in the node test is expanded into an expanded-name using the namespace declarations from the expression context. This is the same way expansion is done for element type names in start and end-tags except that the default namespace declared with xmlns is not used: if the QName does not have a prefix, then the namespace URI is null (this is the same way attribute names are expanded). It is an error if the QName has a prefix for which there is no namespace declaration in the expression context.
See also: *(all nodes), text(), node(), comment(), processing-instruction()
Examples (xslt:xml):Interactive xlab: [xsl:value-of] [xsl:template]