This subchapter applies to:
(1) the State of Texas, including an agency, department, commission, bureau, board, office, council, court, or other entity that is in any branch of state government and that is created by the constitution or a statute of this state, including a university system or a system of higher education;
(2) the governing body of a municipality, county, or special district or authority;
(3) an officer, employee, or other body that is part of a municipality, county, or special district or authority, including a sheriff, municipal police department, municipal attorney, or county attorney; and
(4) a district attorney or criminal district attorney.