Editing XPath 2.0 (section)

== Path expressions ==

The ''location paths'' of [[XPath 1.0]] are referred to in XPath 2.0 as ''path expressions''. Informally, a path expression is a sequence of steps separated by the "<code>/</code>" operator, for example <code>a/b/c</code> (which is short for <code>child::a/child::b/child::c</code>). More formally, however, "<code>/</code>" is simply a binary operator that applies the expression on its right-hand side to each item in turn selected by the expression on the left hand side. So in this example, the expression <code>a</code> selects all the element children of the context node that are named <code>&lt;a&gt;</code>; the expression <code>child::b</code> is then applied to each of these nodes, selecting all the <code>&lt;b&gt;</code> children of the <code>&lt;a&gt;</code> elements; and the expression <code>child::c</code> is then applied to each node in this sequence, which selects all the <code>&lt;c&gt;</code> children of these <code>&lt;b&gt;</code> elements.

The "<code>/</code>" operator is generalized in XPath 2.0 to allow any kind of expression to be used as an operand: in XPath 1.0, the right-hand side was always an axis step. For example, a function call can be used on the right-hand side. The typing rules for the operator require that the result of the first operand is a sequence of nodes. The right hand operand can return either nodes or atomic values (but not a mixture). If the result consists of nodes, then duplicates are eliminated and the nodes are returned in ''document order'', an ordering defined in terms of the relative positions of the nodes in the original XML tree.

In many cases the operands of "<code>/</code>" will be axis steps: these are largely unchanged from XPath 1.0, and are described in the article on [[XPath 1.0]].