CSS <custom-ident> Data Type

In CSS, <custom-ident> is a generic data type that represents a custom identifier defined by the author of the style sheet.

Some CSS properties accept a <custom-ident> value so that you can create an arbitrary value that serves as an identifier. When you see <custom-ident> (including the < and >) anywhere in the CSS specifications, this refers to the fact that the value can be an arbitrary author-defined identifier.

For example, the counter-reset property accepts the following values.

So you could write something like this:

Here's a working example:

So in this example, I created two <custom-ident>s; one called h1-counter and another called h2-counter. And I used counter-increment and counter-reset to set/change the values of those identifiers as required.

Naming <custom-ident> Values

A <custom-ident> can be any valid CSS identifier that would not be misinterpreted as a pre-defined keyword in that property's value definition.

A <custom-ident> can include the following characters:

A <custom-ident> must also adhere to the following rules:

Here are some examples of valid <custom-ident> values:

CSS Specifications