What nd5y posted is a perfect example. Each of those columns is a zone, and each zone has the same number of channels (16 is typical). Think of it as the banks or systems in your scanner; the only difference is that a radio can only monitor one zone at a time. Each department has their own template which the vendor (at least initially) will program for them. In Michigan, agencies on the MPSCS have to follow certain guidelines; Zone A is reserved for MSP; Zones G, H, I, & J are for statewide event talkgroups; Zone F is for the national interoperability channels (8CALL90, etc). Most all of the other zones (primarily B, C, D, & E) can be programmed to the individual agency's needs.