Axes

Article
11/18/2015

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4/8/2010

An axis is used in a location path to specify the tree relationship between the nodes selected by the location step and the context node.

Axes	Description
ancestor	Contains the ancestors of the context node; the ancestors of the context node consist of the parent of the context node and the parent's parent and so on; thus the ancestor axis will always include the root node unless the context node is the root node.
ancestor-or-self	Contains the context node and the ancestors of the context node; thus the ancestor axis will always include the root node.
attribute	Contains the attributes of the context node; the axis will be empty unless the context node is an element.
child	Contains the children of the context node.
descendant	Contains the descendants of the context node; a descendant is a child or a child of a child and so on; thus the descendant axis never contains attribute or namespace nodes.
descendant-or-self	Contains the context node and the descendants of the context node.
following	Contains all nodes in the same document as the context node that are after the context node in document order, excluding any descendants and excluding attribute nodes and namespace nodes.
following-sibling	Contains all the following siblings of the context node; if the context node is an attribute node or name space node, the following-sibling axis is empty.
namespace	Contains the name space nodes of the context node; the axis will be empty unless the context node is an element.
parent	Contains the parent of the context node, if there is one.
preceding	Contains all nodes in the same document as the context node that are before the context node in document order, excluding any ancestors and excluding attribute nodes and name space nodes.
preceding-sibling	Contains all the preceding siblings of the context node; if the context node is an attribute node or name space node, the preceding-sibling axis is empty.
self	Contains just the context node itself.

Remarks

name space
Each element has an associated set of name space nodes, one for each distinct name space prefix that is in scope for the element (including the xml prefix, which is implicitly declared by the XML Name spaces Recommendation) and one for the default name space if one is in scope for the element. The element is the parent of each of these name space nodes; however, a name space node is not a child of its parent element. Elements never share name space nodes; if one element node is not the same node as another element node, then none of the name space nodes of the one element node will be the same node as the name space nodes of another element node. This means that an element will have a name space node:
- For every attribute on the element whose name starts with xmlns:
- For every attribute on an ancestor element whose name starts xmlns: unless the element itself or a nearer ancestor redeclares the prefix
- For an xmlns attribute, if the element or some ancestor has an xmlns attribute, and the value of the xmlns attribute for the nearest such element is non-empty
The "sample" element in the following instance.
```
<A xmlns="urn:A">
  <B xmlns:test="sample">
    <sample xmlns:sampletest="sampletest"/>
  </B>
</A>
```
Contains the following name space nodes:

xmlns="urn:A"

xmlns:test="sample"

xmlns:sampletest="sampletest"

The "sample" element in the following instance.
```
<A xmlns="urn:A">
  <B  xmlns:test="sample">
    <sample xmlns:sampletest="sampletest" xmlns:bar="test"/>
  </B>
</A>
```
Contains the following name space nodes:

xmlns:sampletest="sampletest"

xmlns:test="test"

Note

An attribute "undeclares" the default name space.

A name space node has an expanded-name: the local part is the name space prefix (this is empty if the name space node is for the default name space); the name space Uniform Resource Identifier (URI) is always null.

The string-value of a name space node is the name space URI that is being bound to the name space prefix; if it is relative, it must be resolved just like a name space URI in an expanded-name.

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Axes

Remarks

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Concepts

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