Node tests

A node test is a condition that must be true for each node that is selected by an axis step. The node test can be expressed as a name test or a kind test. A name test selects nodes based on the name of the node. A kind test selects nodes based on the kind of node.

Name tests

A name test consists of a QName or a wildcard. When a name test is specified in an axis step, the step selects the nodes on the specified axis that match the QName or wildcard. If the name test is specified on the attribute axis, the step selects any attributes that match the name test. Otherwise, on all other axes, the step selects any elements that match the name test. For the QNames to match, the expanded QName of the node must be equal (on a codepoint basis) to the expanded QName that is specified in the name test. Two expanded QNames are equal if their namespace URIs are equal and their local names are equal (even if their namespace prefixes are not equal).

Important: Any prefix that is specified in a name test must correspond to one of the statically known namespaces for the expression. For name tests that are performed on the attribute axis, unprefixed QNames have no namespace URI. For name tests that are performed on all other axes, unprefixed QNames have the namespace URI of the default element namespace.

Table 1 describes the name tests that are supported in XQuery.

Table 1. Supported name tests in XQuery
Test	Description	Examples
`QName`	Matches any nodes (on the specified axis) whose QName is equal to the specified QName. If the axis is an attribute axis, this test matches attribute nodes that are equal to the specified QName. On all other axes, this test matches element nodes that are equal to the specified QName.	In the expression `child::para`, the name test `para` selects all of the `para` elements on the child axis.
*	Matches all nodes on the specified axis. If the axis is an attribute axis, this test matches all attribute nodes. On all other axes, this test matches all element nodes.	In the expression, `child::`, the name test matches all elements on the child axis.

Kind tests

When a kind test is specified in an axis step, the step selects only those nodes on the specified axis that match the kind test. Table 2 describes the kind tests that are supported in XQuery.

Table 2. Supported kind tests in XQuery
Test	Description	Examples
node()	Matches any node on the specified axis.	In the expression `child::node()`, the kind test `node()` selects any nodes on the child axis.
text()	Matches any text node on the specified axis.	In the expression `child::text()`, the kind test `text()` selects any text nodes on the child axis.
comment()	Matches any comment node on the specified axis.	In the expression `child::comment()`, the kind test `comment()` selects any comment nodes on the child axis.
processing-instruction(NCName)	Matches any processing-instruction node (on the specified axis) whose name (called its "PITarget" in XML) matches the NCName that is specified in this name test.	In the expression `child::processing-instruction( xml-stylesheet)`, the kind test `processing-instruction( xml-stylesheet)` selects any processing instruction nodes on the child axis whose PITarget is xml-stylesheet.
processing-instruction(StringLiteral)	Matches any processing-instruction node (on the specified axis) whose name matches the string literal that is specified in this test. This node test provides backwards compatibility with XQuery 1.0.	In the expression `child::processing-instruction("xml-stylesheet")`, the kind test `processing-instruction("xml-stylesheet")` selects any processing instruction nodes on the child axis whose PITarget is xml-stylesheet.
element()	Matches any element node on the specified axis.	In the expression `child::element()`, the kind test `element()` selects any element nodes on the child axis.
element(QName)	Matches any element node (on the specified axis) whose name matches the qualified name that is specified in this test.	In the expression `child::element("price")`, the kind test `element("price")` selects any element nodes on the child axis whose name is price.
element(*)	Matches any element node on the specified axis.	In the expression `child::element()`, the kind test `element()` selects any element nodes on the child axis.
attribute()	Matches any attribute node on the specified axis.	In the expression `child::attribute()`, the kind test `attribute()` selects any attribute nodes on the child axis.
attribute(QName)	Matches any attribute node (on the specified axis) whose name matches the qualified name that is specified in this test.	In the expression `child::attribute("price")`, the kind test `attribute("price")` selects any attribute nodes on the child axis whose name is price.
attribute(*)	Matches any attribute node on the specified axis.	In the expression `child::attribute()`, the kind test `attribute()` selects any attribute nodes on the child axis.
document-node()	Matches any document node on the specified axis.	In the expression `child::document-node()`, the kind test `document-node()` selects any document nodes on the child axis.
document-node(element(QName))	Matches any document node on the specified axis that has only one element node (on the specified axis), and the name of the node matches the qualified name that is specified in this test.	In the expression `child::document-node(element("price"))`, the kind test `document-node(element("price"))` selects any document nodes on the child axis that have a single element whose name is price.
document-node(element(*))	Matches any document node on the specified axis that has element nodes.	In the expression `child::document-node(element())`, the kind test `document-node(element())` selects any document nodes on the child axis that have element nodes.