AtRule describes an Item with a name, a prelude consisting of a list of component values, and an optional block consisting of a simple {} block.

Block describes an Item that is a {}, (), [] block.

ComponentValue describes an Item that is either one of the preserved tokens, a function, or a simple block.

Declaration describes an Item that associates a property or descriptor name with a value.

Function describes an Item with a name and a value consisting of a list of component values.

An Item is a value in a tree produced by the parser.

QualifiedRule describes an Item with a prelude consisting of a list of component values, and a block consisting of a simple {} block.

PreservedToken describes an Item that is any token produced by the tokenizer except for <function-token>, <{-token>, <(-token>, or <[-token>.