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<h1>Axis steps</h1>
<p>The basic primitive for accessing a source document is the <i>axis step</i>. Axis steps
may be combined into path expressions using the path operators <code>/</code> and <code>//</code>,
and they may be filtered using filter expressions in the same way as the result of any other
expression.</p>
<p>An axis step has the basic form <code>axis :: node-test</code>, and selects nodes on a given axis
that satisfy the node-test. The axes available are:</p>
<table>
<tr>
<td content="para">
<p>ancestor</p>
</td>
<td content="para">
<p>Selects ancestor nodes starting with the current node and ending
with the document node</p>
</td>
</tr>
<tr>
<td content="para">
<p>ancestor-or-self</p>
</td>
<td content="para">
<p>Selects the current node plus all ancestor nodes</p>
</td>
</tr>
<tr>
<td content="para">
<p>attribute</p>
</td>
<td content="para">
<p>Selects all attributes of the current node (if it is an element)</p>
</td>
</tr>
<tr>
<td content="para">
<p>child</p>
</td>
<td content="para">
<p>Selects the children of the current node, in documetn order</p>
</td>
</tr>
<tr>
<td content="para">
<p>descendant</p>
</td>
<td content="para">
<p>Selects the children of the current node and their children, recursively
(in document order)</p>
</td>
</tr>
<tr>
<td content="para">
<p>descendant-or-self</p>
</td>
<td content="para">
<p>Selects the current node plus all descendant nodes</p>
</td>
</tr>
<tr>
<td content="para">
<p>following</p>
</td>
<td content="para">
<p>Selects the nodes that follow the current node in document order,
other than its descendants</p>
</td>
</tr>
<tr>
<td content="para">
<p>following-sibling</p>
</td>
<td content="para">
<p>Selects all subsequent child nodes of the same
parent node</p>
</td>
</tr>
<tr>
<td content="para">
<p>namespace</p>
</td>
<td content="para">
<p>Selects all the in-scope namespaces for an element (this axis
is deprecated in XPath 2.0, but Saxon continues to support it)</p>
</td>
</tr>
<tr>
<td content="para">
<p>parent</p>
</td>
<td content="para">
<p>Selects the parent of the current node</p>
</td>
</tr>
<tr>
<td content="para">
<p>preceding</p>
</td>
<td content="para">
<p>Selects the nodes that precede the current node in document order,
other than its ancestors</p>
</td>
</tr>
<tr>
<td content="para">
<p>preceding-sibling</p>
</td>
<td content="para">
<p>Selects all preceding child nodes of the same
parent node</p>
</td>
</tr>
<tr>
<td content="para">
<p>self</p>
</td>
<td content="para">
<p>Selects the current node</p>
</td>
</tr>
</table>
<p>When the child axis is used, <code>child::</code> may be omitted, and when the attribute
axis is used, <code>attribute::</code> may be abbviated to <code>@</code>. The expression
<code>parent::node()</code> may be shortened to <code>..</code></p>
<p><i>The expression <code>.</code> is no longer synonymous with <code>self::node()</code>,
since it may now select items that are not nodes. If the context item is not a node, any use of a
path expression will raise an error.</i></p>
<p>The node-test may be, for example:</p>
<ul>
<li content="para">
<p>a node name</p>
</li>
<li content="para">
<p>
<code>prefix:*</code> to select nodes in a given namespace</p>
</li>
<li content="para">
<p>
<code>*:localname</code> to select nodes with a given local name, regardless of namespace</p>
</li>
<li content="para">
<p>
<code>text()</code> (to select text nodes)</p>
</li>
<li content="para">
<p>
<code>node()</code> (to select any node)</p>
</li>
<li content="para">
<p>
<code>processing-instruction()</code> (to select any processing instruction)</p>
</li>
<li content="para">
<p>
<code>processing-instruction('literal')</code> to select processing instructions with the given name
(target)</p>
</li>
<li content="para">
<p>
<code>comment()</code> to select comment nodes</p>
</li>
<li content="para">
<p>
<code>element()</code> or <code>element(*)</code> to select any element node</p>
</li>
<li content="para">
<p>
<code>element(N)</code> to select any element node named N</p>
</li>
<li content="para">
<p>
<code>element(*, T)</code> to select any element node whose type annotation
is T, or a subtype of T</p>
</li>
<li content="para">
<p>
<code>element(N, T)</code> to select any element node whose name is N
and whose type annotation is T, or a subtype of T</p>
</li>
<li content="para">
<p>
<code>schema-element(N)</code> to select any element node whose name is N,
or an element in the substitution group of N, that conforms to the schema-defined
type for a global element declaration named N in an imported schema</p>
</li>
<li content="para">
<p>
<code>attribute</code> or <code>attribute(*)</code> to select any attribute node</p>
</li>
<li content="para">
<p>
<code>attrbute(N)</code> to select any attribute node named N</p>
</li>
<li content="para">
<p>
<code>attribute(*, T)</code> to select any attribute node whose type annotation
is T, or a subtype of T</p>
</li>
<li content="para">
<p>
<code>attribute(N, T)</code> to select any attribute node whose name is N
and whose type annotation is T, or a subtype of T</p>
</li>
<li content="para">
<p>
<code>schema-attribute(N)</code> to select any attribute node whose name is N,
that conforms to the schema-defined
type for a global attribute declaration named N in an imported schema</p>
</li>
</ul>
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<tr>
<td>
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</td>
</tr>
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