In XML, element names can be originated and changed to reflect the type of information contained in the document.
This level of flexibility may cause problems if separate documents encode different kinds of information, but use the same identifiers for the element names.
For example, using XPath: The term collision domain may also be used to refer to a system in which a single name or identifier is open to multiple interpretations by different layers or processing.
The notion of a namespace has been widely adopted as a software programming practice to avert undesired clashes.
Note that its use in the networking field is superficially similar, but quite different in reality.