Standardisation
In 2010, and onwards, there are efforts to standardise the about URI scheme, and define the processing requirements for some specific URIs, in the IETF Applications Area Working Group (APPSAWG). In August 2012, it was published as an official Request for Comments as RFC 6694. Note that Opera ASA, the proponents, had long used and advocated alternative browser specific URIs. The about URIs that are known to be defined for specific purposes are listed below.
| URI | Purpose |
|---|---|
| about:blank | Returns a blank HTML document with the media type text/html and character encoding UTF-8. This is widely used to load blank pages into browsing contexts, such as iframes within HTML, which may then be modified by scripts. |
| about:legacy-compat | A reserved, though unresolvable, URI defined within HTML5 intended for use in the DOCTYPE designed for compatibility with some legacy authoring tools, such as XSLT, which may not be capable of outputting the more common, shorter alternative that lacks both the PUBLIC and SYSTEM identifiers. |
| about:srcdoc | A reserved, though unresolvable, URI defined within HTML5 intended to be the URI navigated to within iframes whose content comes from the srcdoc attribute |
| about:invalid | A reserved, though unresolvable, URI defined within CSS Values and Units module, intended as a non-existent document with a generic error condition for use where a URI is necessary, but where no actual resource is desired. |
Read more about this topic: About URI Scheme