Types

CSS basic data types define the kinds of values (keywords and units) accepted by CSS properties and functions.

Structure for types

A type object looks like the following example.

"length": {
  "groups": [
    "CSS Types"
  ],
  "status": "standard"
},

The 2 properties are both required.

groups (array of strings): CSS is organized in modules like "CSS Types" or "CSS Color". MDN organizes features in these groups as well — groups should contain the name of the module(s) the type is defined in.
status (enum string): This is either standard, nonstandard, or experimental depending on the standardization status of the feature.

There is another property that is optional:

mdn_url (string): a URL linking to the type's page on MDN. This URL must omit the localization part of the URL (such as en-US/).