The <source> element contains a description of the resource. Alternatively, the @href or @keyref attributes can be used to reference a description of the resource. It is implementation-dependent what it means when the element has both content and an attribute-based reference to another resource.
This element is equivalent to the <Source> element in Dublin Core.
See appendix for information about this element in OASIS document type shells.
<prolog> <source>Somewhere, someplace</source> </prolog>
- Provides a reference to a resource from which the present resource is derived. See The @href attribute for detailed information on supported values and processing implications.