Which statement about syntax items is true:

A syntax item represents a specific marker character such as a delimiter or structural indicator used in the data stream, and a restriction list is mandatory because it defines precisely which character values are valid for that item. Without a restriction list, the parser would have no basis for recognizing the syntax item when scanning the data stream, making the type tree definition incomplete. The restriction list is therefore a required element of any valid syntax item definition, not an optional enhancement.

Syntax items do not have a universal maximum length of 1 byte; the length is determined by the character encoding and the specific type tree definition in use.

A syntax item's value is not required to originate from input data; it is defined as a fixed or constant value within the type tree itself and is not derived from the incoming data stream.

Syntax items can be used as variable initiators to signal the start of a data structure, which is a valid and common use of syntax items in type tree construction.