1         c) and d); VHF networks can cover only a limited range, and while repeater stations can extend the area covered by the network, but are not indispensable for the function of a local network.

2         a) and b); shortwave antennas are bigger than VHF antennas, and VHF networks carry data as well as voice communication.

3         b) and d); for technical, operational and regulatory reasons, communication between stations of different radio services are not normally possible, and the range of "wireless LAN" connections between PCs or laptops is far smaller than that of an average VHF network.

4         d); all these services use voice and data modes and operate in the VHF and the shortwave frequency spectrum, however not all voice or data mode each of the services uses are compatible with all respective modes used by any other service; separate frequency bands are internationally allocated to each service, and while in an emergency the use of other than officially allocated frequencies is permitted, the technical specifications of the equipment do often not allow this.