CSS - <custom-ident>
The <custom-ident>
CSS data value denotes an arbitrary user-defined string used as an identifier. It is case-sensitive and in each context, several values are excluded to prevent misinterpretations.
Example
These are valid identifiers:
nono79 A mix of alphanumeric characters and numbers ground-level A mix of alphanumeric characters and a dash -test A dash followed by alphanumeric characters _internal An underscore followed by alphanumeric characters \22 toto A Unicode character followed by a sequence of alphanumeric characters bili\.bob The period is correctly escaped
These are invalid identifiers:
34rem It must not start with a decimal digit. -12rad It must not start with a dash followed by a decimal digit. bili.bob Only alphanumeric characters, _ and - need not to be escaped. --toto It must not start with two dashes. 'bilibob' It isn't a <user-ident> but a <a href="css/string" title="The <string> CSS data type represents a string. It is formed by a Unicode characters delimited by either double (") or single (') quotes. A double quoted string cannot contain double quotes unless escaped using a backslash (\). The same practice applies for single quoted strings, they cannot contain single quotes unless escaped using a backslash (\). The backslash character must be escaped to be part of the string."><code><string></code></a>. "bilibob" It isn't a <user-ident> but a <a href="css/string" title="The <string> CSS data type represents a string. It is formed by a Unicode characters delimited by either double (") or single (') quotes. A double quoted string cannot contain double quotes unless escaped using a backslash (\). The same practice applies for single quoted strings, they cannot contain single quotes unless escaped using a backslash (\). The backslash character must be escaped to be part of the string."><code><string></code></a>.
Syntax
Its syntax is similar to the CSS identifier one, except that it is case-sensitive: a <custom-ident>
is a sequence of characters where characters can be:
- any alphanumeric character (
'A'
to'Z'
, or'a'
to'z'
), - any decimal digit (
'0'
to'9'
), - a dash (
'-'
) - an underscore (
'_'
), - a escaped character (with a backslash,
'\'
), - or a Unicode character (in the format of a backslash followed by one to six hexadecimal digits, its Unicode code point).
The first character must not be a decimal digit nor a dash ('-'
) followed by a decimal digit or another dash. A <custom-ident>
must not be placed between single or double quotes as it would be identical to a <string>
.
Note that id1
, Id1
, iD1
and ID1
are all different identifiers as they are case-sensitive. In the opposite, as there are several ways to escape a character, toto\?
and toto\3F
are the same identifiers.
Description
The <custom-ident>
CSS data value denotes an arbitrary user-defined string used as an identifier. It is case-sensitive and in each context, several values are excluded to prevent misinterpretations.
Browser Compatibility
As this type is not a real type but a convenience type used to simplify the description of allowed values, there is no browser compatibility information stricto sensu.
See Also
- CSS Data Types:
<angle>
,<blend-mode>
,<color>
,<custom-ident>
,<frequency>
,<gradient>
,<image>
,<length>
,<number>
,<percentage>
,<position>
,<ratio>
,<resolution>
,<shape>
,<string>
,<time>
,<timing-function>
,<uri>
Specifications
In order to prevent ambiguity, each property using <custom-ident>
also defined a specific list of forbidden values:
animation-name
- Forbids the global CSS values,
unset
,initial
, andinherit
, and the valuenone
. counter-reset
counter-increment
- Forbids the global CSS values,
unset
,initial
, andinherit
, and the valuenone
. @counter-style
list-style-type
- Forbids the global CSS values,
unset
,initial
, andinherit
, as well as the valuesnone
,inline
, andoutside
. Also quite a few predefined values are implemented by the different browsers:disc
,circle
,square
,decimal
,cjk-decimal
,decimal-leading-zero
,lower-roman
,upper-roman
,lower-greek
,lower-alpha
,lower-latin
,upper-alpha
,upper-latin
,arabic-indic
,armenian
,bengali
,cambodian
,cjk-earthly-branch
,cjk-heavenly-stem
,cjk-ideographic
,devanagari
,ethiopic-numeric
,georgian
,gujarati
,gurmukhi
,hebrew
,hiragana
,hiragana-iroha
,japanese-formal
,japanese-informal
,kannada
,katakana
,katakana-iroha
,khmer
,korean-hangul-formal
,korean-hanja-formal
,korean-hanja-informal
,lao
,lower-armenian
,malayalam
,mongolian
,myanmar
,oriya
,persian
,simp-chinese-formal
,simp-chinese-informal
,tamil
,telugu
,thai
,tibetan
,trad-chinese-formal
,trad-chinese-informal
,upper-armenian
,disclosure-open
, anddisclosure-close
. will-change
- Forbids the global CSS values,
unset
,initial
,inherit
, as well as the valueswill-change
,auto
,scroll-position
, andcontents
.
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/css/custom-ident