html相关定义

doctype：

What is it?

The !DOCTYPE declaration is a top-level tag-like reference known as a Public Text Identifier. It should appear at the very beginning of an HTML/XHTML document in order to identify the content of the document as conforming (theoretically) to a particular HTML DTD specification. Historically, including a DTD was not required by browsers; they just interpreted a document according to what elements and attributes it understood. That has now changed (see the section on DOCTYPE switching below.)

The quoted segment within a !DOCTYPE declaration is called a Formal Public Identifier (FPI.) Every distinct DTD variation will have its own unique FPI string.

http://www.rfc-editor.org/rfc/rfc1866.txt

!DOCTYPE Switching links

Official References

http://www.mozilla.org/docs/web-developer/quirks/doctypes.html

Mozilla's documentation and table on which DTDs trigger which mode (by David Baron)

http://dbaron.org/mozilla/quirklist

David Baron's list of differences between quirks and standards mode (probably can be called "official")

http://msdn.microsoft.com/library/en-us/dnie60/html/cssenhancements.asp?frame=true

Internet Explorer's "Enhancements in IE6": documentation and mode/behavior differences

http://www.opera.com/docs/specs/doctype/

Opera's documentation and mode/behavior differences

Other References

http://gutfeldt.ch/matthias/articles/doctypeswitch.html

Matthias Gutfeldt's "Doctype switching and standards compliance: An overview"; a great up-to-date discussion of the topic with many additional links for more information.

http://www.hut.fi/u/hsivonen/doctype.html

Henri Sivonen's "Activating the right layout mode using the Doctype declaration"; another great discussion of the topic.

Boring Copyright Stuff...