Uniform Resource Identifier (URI) Schemes 2012-06-12 2016-09-06 First Come First Served blank The about:blank URI references a blank page. invalid The about:invalid URI references a non-existent document with a generic error condition. It can be used when a URI is necessary, but the default value shouldn't be resolveable as any type of document. srcdoc Used as the document's address of iframe srcdoc documents in HTML. legacy-compat For use in DOCTYPEs in HTML documents when needed for compatibility with XML tools. html-kind The about:html-kind URI identifies the vocabulary of kind values in HTML specifications from W3C and WhatWG. CSS Working Group mailto:www-style&w3.org 2012-07-12 David Singer mailto:singer&apple.com 2016-09-06 Ian Hickson mailto:ian&hixie.ch 2012-08-09