Storage specifications for 500-metre-grid terrain data / by J.H. Whitteker. : Co24-3/7-92-002E-PDF

"Terrain data for much of Canada and some adjoining U.S. territory are stored compactly in a binary format. The format was designed to be used for obtaining elevations and surface type information along radio propagation paths, but it may be used whenever compact, rapidly-accessible terrain data are required. Terrain points are the intersections of a 500-metre grid defined on the UTM (Universal Transverse Mercator) co-ordinate system. A teach point, an elevation is stored, and a code indicating surface type (bare ground, tree covered, lake, sea, buildings) is also stored wherever it is available. The information for each point occupies 16 bits. A record occupies 1024 bytes, and corresponds to a 7.5 x 15.5-km rectangle. With this arrangement, points that are geographically close together are usually also close together in the data file. A file represents an area 40 of latitude by 6° of longitude. Each file contains its own index in the first six records"--Abstract.

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