Use of profile attribute in HTML head tag

Question

What is the use of profile attributes in the HTML tag?

I happened to read about it in here : http://www.w3schools.com/tags/tag_head.asp.

Answer 1

Often, the header of a document contains a number of tags used to convey additional information about the document to the browser. In the future, authors may use predefined profiles of standard document metadata to better describe their documents. The profile attribute supplies the URL of the profile associated with the current document.

The format of a profile and how a browser might use it are not yet defined; this attribute is primarily a placeholder for future development.

FROM:: HTML & XHTML: The Definitive Guide, Sixth Edition, by Chuck Musciano and Bill Kennedy. Copyright 2007 O’Reilly Media, Inc., 978-0-596-52732-7.