DocRegExt xs doc A description of a document/education-like resource. A natural-language document. Natual-language documents suitable for registration include worked-out use cases, tutorials, courses, or even material like reference cards, provided they cover Virtual Observatory techniques. We consider all translations of a document as one resource. Individual translations are defined as doc:DocFile-typed capabilities. An “edition” (typically: translation) of the document. Although for a while, multiple editions of the document in one language may be given (corresponding perhaps to two “major” versions), in general, only the latest version of the document per language should be given. At least one vr:WebBrowser-typed interface with role="rendered" must be present. The access URL of the interface points to a rendered version of the edition (preferably in PDF, but HTML is acceptable, too). Editors are strongly encourated to also provide an interface with role="source", the accessURL of which should point to an editable version of the document, a version controlled repository, or the like. The language this document is (mainly) written in, as an RFC 3066 language code. The country codes must be given in all lowercase. This results in strings like en-us, de-de, or es-mx. This language is also the language for locTitle, irrespective or that element's xml:lang setting. The translated document's title in the language specified by the language sibling. It is recommended to set this element's xml:lang element to the same value as the language sibling. The reason xml:lang is not used in the first place is that with an extra element, enforcing that the content language is given is more straightforward.