HTML and CSS Reference
■ In HTML, <![CDATA[...]]> is a bogus comment ; that is, the sequence of characters is considered as
regular character data. In XHTML, <![CDATA[...]]> is a character data section; in other words, a sequence of characters
to be displayed rather than processed as XML. Without unescape, these sections would result in a well-formedness error
HTML5 supports the following data types:
• Te x t : If Unicode encoded, a sequence of Unicode characters that does not contain U+0000
characters, control characters other than space characters, or any permanently undefined
• String : An arbitrary mixture of text and character references.
• Token : A string without space characters.
• Browsing-context name : A string that does not start with an underline ( _ ) character and is at
least one character long.
• Browsing-context name or keyword : A string that is either a browsing-context name or one of
the following literal strings: _blank , _self , _parent , or _top .
• ID : A string without space characters that is at least one character long.
• Name : A string without space characters that is at least one character long.
• Hash-name reference : A string that starts with a # character.
• Number : Integer, positive integer, non-negative integer, floating-point number, positive
floating-point number, or non-negative floating-point number.
• Date and time : A date-time as defined in RFC 3339, with the additional constraints that the
literal letters T and Z must always be uppercase and that the date + full year is described as
four or more digits representing a number greater than 0.
• URL : A valid IRI reference as defined in RFC 3987.
• MIME type : A string identifying a valid MIME media type defined by RFC 2046.
• Character encoding name : A character encoding a name or alias from the IANA registry.
• Meta-charset string : A string with the following parts (in that order): the literal string
text/html; , one or more optional space characters, the literal string charset= , and a
character encoding name (HTML5) or the string UTF-8 (XHTML5).
• Refresh value : Either a non-negative integer or a string containing a non-negative integer, a ;
character, one or more space characters, the string url= , and finally a URL (in this order).
• Default-style name : A string.
• Media-query list : A media query list as defined in the W3C specification “Media Queries” .
• Language tag : A language tag as defined in BCP 47 .
• List of key labels : An ordered set of unique space-separated tokens, each of which is exactly
one Unicode codepoint in length.