Question 21 :
Does the XML namespaces recommendation define anything except a two-part naming system for element types and attributes?
This is a very important point and a source of much confusion, so we will repeat it:
THE XML NAMESPACES RECOMMENDATION DOES NOT DEFINE ANYTHING EXCEPT A TWO-PART NAMING SYSTEM FOR ELEMENT TYPES AND ATTRIBUTES.
In particular, they do not provide or define any of the following:
* A way to merge two documents that use different DTDs.
* A way to associate XML namespaces and schema information.
* A way to validate documents that use XML namespaces.
* A way to associate element type or attribute declarations in a DTD with an XML namespace.
Question 22 :
Do XML namespaces apply to entity names, notation names, or processing instruction targets?
XML namespaces apply only to element type and attribute names. Furthermore, in an XML document that conforms to the XML namespaces recommendation, entity names, notation names, and processing instruction targets must not contain colons.
Question 23 :
Who can create an XML namespace?
Anybody can create an XML namespace -- all you need to do is assign a URI as its name and decide what element type and attribute names are in it. The URI must be under your control and should not be being used to identify a different XML namespace, such as by a coworker.
(In practice, most people that create XML namespaces also describe the element types and attributes whose names are in it -- their content models and types, their semantics, and so on. However, this is not part of the process of creating an XML namespace, nor does the XML namespace include or provide a way to discover such information.)
Question 24 :
What is the difference between versions 1.0 and 1.1 of the XML namespaces recommendation?
There are only two differences between XML namespaces 1.0 and XML namespaces 1.1:
* Version 1.1 adds a way to undeclare prefixes. For more information, see question 4.7.
* Version 1.1 uses IRIs (Internationalized Resource Identifiers) instead of URIs. Basically, URIs are restricted to a subset of ASCII characters, while IRIs allow much broader use of Unicode characters. For complete details, see section 9 of Namespaces in XML 1.1.
NOTE: As of this writing (February, 2003), Namespaces in XML 1.1 is still a candidate recommendation and not widely used. PART II: DECLARING AND USING XML NAMESPACES
Question 25 :
Where can I declare an XML namespace?
You can declare an XML namespace on any element in an XML document. The namespace is in scope for that element and all its descendants unless it is overridden.