Definition and Usage
The <user-ident> CSS data value denotes an arbitrary user-defined string used as an identifier.
Its syntax is similar to the CSS identifier one, except that it is case-sensitive: a <user-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 <user-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 they are several way to escape a character, toto\? and toto\3F are the same identifiers.
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 an alphabetic character _internal An underscore followed by alphanumeric characters \22 toto A Unicode character followed by a sequence of alphanumeric character 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 being escaped. --toto It must not start with two dashes. 'bilibob' It isn't an <user-ident>, it is a<string>. "bilibob" It isn't an <user-ident>, it is a<string>.
The <user-ident> data type is mainly used in conjunction with CSS Counters, the counter functional notation and the two related CSS properties, counter-reset and counter-increment.
Compatibility
Desktop browsers
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
|---|---|---|---|---|---|
| Basic support | 2.0 | 1.0 | 8.0 | 9.2 | 3.1 |
Mobile browsers
| Feature | Android | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|
| Basic support | NA | NA | NA | NA | NA |
