post a "namespace document" at the namespaceURI(s)

[pbiron]

When a markup language is defined in a namespace (such as WXR), it is considered good practice to post a "namespace document" at the namespaceURI.

Namespace documents are usually short and sweet and do not constitute full documentation on the markup defined in that namespace. However, they typically contain a link to where that full documentation can be found (see Issue 4: document WXR on DevHub).

Good examples of namespace documents include:

• https://www.w3.org/1999/XSL/Transform
• http://docs.oasis-open.org/ns/cmis/core/200908/

XML applications generally do NOT dereference namespaceURIs, but are certainly not prohibited from doing so. So, posting a namespace document at the namespaceURI(s) should not be undertaken lightly because it might result in increased HTTP hits on .org.

The RSS spec defines , which is an optional child of <channel>, whose value is:

A URL that points to the documentation for the format used in the RSS file....It's for people who might stumble across an RSS file on a Web server 25 years from now and wonder what it is.

WXR 1.3-proposed includes <docs> and WordPress Exporter Redux outputs it, with a value that is the same as the WXR 1.3-proposed namespaceURI.

[pbiron]

See also https://www.w3.org/2005/07/13-nsuri#nsdoc, which is the W3C's policy regarding namespace documents for namespaces defined in W3C specs.