The <custom-ident>
CSS data type denotes an arbitrary user-defined string used as an identifier. It is case-sensitive, and certain values are forbidden in various contexts to prevent ambiguity.
The syntax of <custom-ident>
is similar to CSS identifiers (such as property names), except that it is case-sensitive. It consists of one or more characters, where characters can be any of the following:
A
to Z
, or a
to z
),0
to 9
),-
),_
),\
),\
, followed by one to six hexadecimal digits, representing its Unicode code point)Note that id1
, Id1
, iD1
and ID1
are all different identifiers as they are case-sensitive. On the other hand, as there are several ways to escape a character, toto\?
and toto\3F
are the same identifiers.
A <custom-ident>
must not be placed between single or double quotes as this would be identical to a <string>
. Moreover, the first character must not be a decimal digit, nor a hyphen (-
) followed by a decimal digit or another hyphen.
To prevent ambiguity, each property that uses <custom-ident>
forbids the use of specific values:
animation-name
unset
, initial
, and inherit
), as well as none
.counter-reset
counter-increment
unset
, initial
, and inherit
), as well as none
.@counter-style
list-style-type
unset
, initial
, and inherit
), as well as the values none
, inline
, and outside
. 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
, and disclosure-close
.grid-row-start
grid-row-end
grid-column-start
grid-column-end
span
value.will-change
unset
, initial
, and inherit
), as well as the values will-change
, auto
, scroll-position
, and contents
.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 A correctly escaped period
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 - needn't be escaped. --toto It must not start with two dashes. This would be a custom property. 'bilibob' This would be a <string>. "bilibob" This would be a <string>.
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 as such.
© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/CSS/custom-ident