XML namespaces provide a way to create globally unique names to distinguish between elements and attributes with the same name but of different terminologies. For example, in an XML invoice document for a bookstore, the name "date" could be used by accounting for the date of the order and by order fulfillment for the date of publication.An XML namespace is identified by a Uniform Resource Identifier (URI), a short string that uniquely identifies resources on the Web. The elements and attributes in each namespace can be uniquely identified by prefixing the element or attribute name (the local name) with the URI of the namespace.
You declare an XML namespace using xmlns as part of a namespace declaration attribute. With the namespace declaration attribute, you can associate a prefix with the namespace.
For example, the following namespace declaration attribute
declares the http://www.pre.com namespace
and associates the prefix pre with
this namespace:
xmlns:pre="http://www.pre.com"
If an XML namespace declaration does not specify a prefix, the namespace becomes a default XML namespace. For example, the following element, digicom, declares the namespace http://www.digital_software.com:
<digicom xmlns="http://www.digital_software.com" />
The namespace http://www.digital_software.com is the in-scope default namespace for the element digicom and any child elements that digicom might contain. The child elements of digicom will automatically be in this namespace.
The following namespace declaration is known as the NONAMESPACE declaration:
xmlns=""
The containing element and its child elements are declared to be in no namespace. An element that is in the NONAMESPACE namespace has its namespace prefix and URI set to empty strings.
When a PBDOM_ELEMENT or a PBDOM_ATTRIBUTE is first created, it has no name, and the namespace information is by default set to the NONAMESPACE namespace (that is, its namespace prefix and URI are both empty strings). The SetName method is used to set the local name and the SetNamespace method is used to set the namespace prefix and URI.
The name is required
The name is a required property of a PBDOM_ELEMENT
and PBDOM_ATTRIBUTE, but the namespace information is not.
If a PBDOM_ELEMENT or PBDOM_ATTRIBUTE is retrieved programmatically from a parsed document, then its name and namespace information are inherited from the Element or Attribute contained in the parsed document. However, even after parsing, the name and namespace information of the PBDOM_ELEMENT and PBDOM_ATTRIBUTE can be further modified with the SetName and SetNamespace methods.The name and namespace information are stored separately internally. Changing the name of a PBDOM_ELEMENT or PBDOM_ATTRIBUTE does not affect its namespace information, and changing its namespace information has no effect on its name.
