Free-form human-readable description of the feed format itself. Intended for people who view the feed in a browser, to explain what they just clicked on. This element is generally ignored by feed readers.
If this contains HTML or XHTML, it is sanitized by default.
If this contains HTML or XHTML, certain (X)HTML elements within this value may contain relative URI (Uniform Resource Identifier)`s. If so, they are :ref:`resolved according to a set of rules <advanced.base>.