In this subchapter:
(1) "Board" means the board of managers of a district.
(2) "District" means a regional emergency communications district created under this subchapter.
(3) "Participating jurisdiction" means a county or principal municipality that adopts a resolution to participate in a district created under this subchapter.
(4) "Principal municipality" means the municipality with the largest population in a region.
(5) "Region" means a state planning region established under Chapter 391, Local Government Code.
(6) "Regional planning commission" means a commission or council of governments created under Chapter 391, Local Government Code, for a designated region.