GOM - the Global Overlay Mapping System

Layer Notes - Amateur Radio Prefixes

Prefixes are shown in a number of ways - the design-brief was to make them as quickly understandable as possible. Prefixes are split into three main groups, which are shown on the map as follows:

1. One prefix covers the whole country, without any divisions. Typical examples are F: France. The prefix overlay shows the prefix itself, with no other additions.
    
2. A country has a number of prefix areas, each of which correspond to individual country-regions. A typical example of this is PY:Brazil. The prefix overlay shows the prefix itself, plus the region-borders that contain each prefix sub-division.
    
3. A country has a number of prefix areas, each of which correspond to regions composed of a number of individual country-regions.. A typical example of this is W:United States of America. The prefix overlay shows the prefix itself, plus the region-borders as before. There is, in addition, a red border that shows how a number of individual country-regions are grouped to form each prefix sub-division.
    

The red border is also used to indicate areas composed of many separate islands, for instance, in the Pacific, and in Northern Canada.

Some prefixes are divided into regions corresponding to the number used in the callsign. A typical example of this is HL:Republic of Korea. The prefix overlay may show a universal prefix for the country, and a number for each region, or it may show a separate prefix/number combination (such as HL4) for each region. The choice between the two is purely based on map-room.

Some prefixes are divided into regions corresponding to the first letter used in the callsign, after the prefix and number. A typical example of this is LU:Argentina. The prefix overlay will show a universal prefix for the country, and a letter for each region. A number may or may not be included. The suffix letter is generally shown in a smaller size than the prefix itself.

The size of prefixes used throughout the Global Overlay Mapping System is based purely on map-room and clarity of information. No other meaning is intended or should be inferred.

The best source of prefix information on the Internet is the big list (>350Kb) at AC6V.Com