As used in this chapter —
(1) The term “witness” includes a person whose testimony is desired in any proceeding or investigation by a grand jury or in a criminal action, prosecution, or proceeding.
(2) The term “State” includes the Commonwealth of Puerto Rico, the District of Columbia, the Virgin Islands, Guam, American Samoa, and any other territory or possession of the United States.
(3) The term “summons” includes a subpoena, order, or other notice requiring the appearance of a witness.