Because it is probable that the pattern and detail of the machinery for mutual aid among 2 or more states may differ from that among the states that are party to this compact, this compact contains elements of a broad base common to all states, and nothing in this compact precludes any state from entering into supplementary agreements with another state or affects any other agreements already in force between states. Supplementary agreements may include, but are not limited to, provisions for evacuation and reception of injured and other persons and the exchange of medical, fire, police, public utility, reconnaissance, welfare, transportation and communications personnel, equipment and supplies. [PL 1997, c. 780, §2 (NEW).]