Date: Sep. 25, 1998
Link: http://www.w3.org/XML/1998/06/xmlspec.dtd
Source Author or Organization: W3C

This DTD was originally developed for the XML 1.0 specification itself; the modern version is also used to encode several other W3C specifications, such as XLink, XPointer, DOM, and XML Schema.

There is documentation available for the DTD. Note that if you want to use the XML-encoded version of the XML 1.0 specification itself, you need to use a special one-off version of the DTD, since the original version has long since been lost. The DTD and documentation are maintained by Eve Maler.