MAP(5)                                                     MAP(5)

     NAME
          map - digitized map formats

     DESCRIPTION
          Files used by map(7) are a sequence of structures of the
          form:

               struct {
                    char patchlatitude;
                    char patchlongitude;
                    short n;
                    union {
                         struct {
                              short latitude;
                              short longitude;
                         } point[n];
                         struct {
                              short latitutde;
                              short longitude;
                              struct {
                                   char latdiff;
                                   char londiff;
                              } point[-n];
                         } highres;
                    } segment;
               };

          Patchlatitude and patchlongitude tell to what 10-degree by
          10-degree patch of the earth's surface a segment belongs.
          Their values range from -9 to 8 and from -18 to 17, respec-
          tively, and indicate the coordinates of the southeast corner
          of the patch in units of 10 degrees.

          Each segment of abs(n) points is connected; consecutive seg-
          ments are not necessarily related.  Latitude and longitude
          are measured in units of 0.0001 radian.  If n is negative,
          then differences to the first and succeeeding points are
          measured in units of 0.00001 radian.  Latitude is counted
          positive to the north and longitude positive to the west.

          The patches are ordered lexicographically by patchlatitude
          then patchlongitude. A printable index to the first segment
          of each patch in a file named map is kept in an associated
          file named map.x.  Each line of an index file contains
          patchlatitude, patchlongitude and the byte position of the
          patch in the map file.

     SEE ALSO
          map(7), map(3)