CentraSite is an XML registry and repository. In XML, a namespace identifies elements or attributes as belonging to a particular set of definitions. If several XML documents use the same element name or attribute name to denote different things, namespaces can be used to treat them as distinct objects. Elements marked as belonging to one particular namespace can, for example, be processed separately from the others, if required, by using filtering mechanisms, such as that provided by the XSLT stylesheet language.

When you create your own object types, you are prompted for a namespace. This is used as a namespace qualifier for the elements and attributes in the object type's schema definition.

The following example shows why namespaces are important: If you wish to import an object type definition from another CentraSite installation, and an object type of the same name but with a different definition already exists in your installation, it is nevertheless possible to import the object type definition as long as the namespaces differ.

A namespace is specified as a URL, for example, http://www.MyCompany.com/MyDepartment. The URL does not need to be the address of a real Web location, but it should be chosen to be unique to your business organization and represent your company or department as precisely as possible. This ensures that if your ontology is ever used in the same environment as an ontology from another organization, the chances of having the same namespace name are minimized.