HTML and CSS Reference
In-Depth Information
■
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
in XML.
Caution
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
Unicode characters.
•
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” [35].
•
Language tag
: A language tag as defined in BCP 47 [36].
•
List of key labels
: An ordered set of unique space-separated tokens, each of which is exactly
one Unicode codepoint in length.
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