GRASS ASCII vector format specification

       A  vector  map  in  GRASS  native  vector format may contain a mix of primitives including
       points, lines, boundaries, centroids, areas, faces, and kernels. The  GRASS  ASCII  vector
       format may contain also a header with various metadata (see example below).

       The  header  is similar as the head file of vector binary format but contains bounding box
       also. Key words are:
       ORGANIZATION
       DIGIT DATE
       DIGIT NAME
       MAP NAME
       MAP DATE
       MAP SCALE
       OTHER INFO
       ZONE
       WEST EDGE
       EAST EDGE
       SOUTH EDGE
       NORTH EDGE
       MAP THRESH

       The body begins with the row:
       VERTI:
       followed by records of primitives:
       TYPE NUMBER_OF_COORDINATES [NUMBER_OF_CATEGORIES]
        X Y [Z]
       ....
        X Y [Z]
       [ LAYER CATEGORY]
       ....
       [ LAYER CATEGORY]
       Everything above in [ ] is optional.

       The primitive codes are as follows:

           •   ’P’: point

           •   ’L’: line

           •   ’B’: boundary

           •   ’C’: centroid

           •   ’F’: face (3D boundary)

           •   ’K’: kernel (3D centroid)

           •   ’A’: area (boundary) - better use ’B’; kept only for backward compatibility
       The coordinates are listed following the initial line containing the primitive  code,  the
       total  number  of  coordinates in the series, and (optionally) the number of categories (1
       for a single layer, higher for multiple layers).  Below that 1 or several lines follow  to
       indicate the layer number and the category number (ID).

       The order of coordinates is
       X Y [Z]
       In pre-GRASS 6 versions of the ASCII format, the order of coordinates was different:
       Y X

       Latitude/Longitude  data  may  be  given  in  a  number  of ways.  Decimal degrees must be
       positive or negative instead of using a hemisphere letter. Mixed coordinates  must  use  a
       hemisphere  letter. Whole minutes and seconds must always contain two digits (example: use
       167:03:04.567; and not 167:3:4.567).
       Acceptable formats:
       key: D=Degrees; M=Minutes; S=Seconds; h=Hemisphere (N,S,E,W)

           •   (+/-)DDD.DDDDD

           •   DDDh

           •   DDD:MMh

           •   DDD:MM.MMMMMh

           •   DDD:MM:SSh

           •   DDD:MM:SS.SSSSSh

EXAMPLES

       ORGANIZATION: GRASS Development Team
       DIGIT DATE:   1/9/2005
       DIGIT NAME:   -
       MAP NAME:     test
       MAP DATE:     2005
       MAP SCALE:    10000
       OTHER INFO:   Test polygons
       ZONE:  0
       MAP THRESH:   0.500000
       VERTI:
       B  6
        5958812.48844435 3400828.84221011
        5958957.29887089 3400877.11235229
        5959021.65906046 3400930.7458436
        5959048.47580612 3400973.65263665
        5959069.92920264 3401032.64947709
        5958812.48844435 3400828.84221011
       C  1 1
        5958952.42189184 3400918.23126419
        1 20
       B  4
        5959010.9323622 3401338.36037757
        5959096.7459483 3401370.54047235
        5959091.38259917 3401450.99070932
        5959010.9323622 3401338.36037757
       C  1 1
        5959063.08352122 3401386.98533277
        1 21
       In this case the vector map contains 2 boundaries (first boundary with 6 vertices,  second
       with  4  vertices)  without category and 2 centroids with category number 20 and 21 (layer
       1).

SEE ALSO

        v.in.ascii, v.out.ascii, v.edit

SOURCE CODE

       Available at: GRASS ASCII vector format specification source code (history)

       Accessed: unknown

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