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/*! \page vlibAscii Vector ASCII Format
by GRASS Development Team (https://grass.osgeo.org)
\tableofcontents
\section vlibAsciiMain Vector ASCII Format Specifications
The GRASS ASCII vector map format may contain a mix of primitives
including points, lines, boundaries, centroids, faces, and
kernels. The format may also contain a header with various metadata
(see example below).
Vector map can be converted to the ASCII representation at user level
by <tt>v.out.ascii format=standard</tt> command.
See \ref vlibAsciiFn for list of related functions.
The header is similar as the head file of vector binary format (see
\ref vlibHeadFileFormat) but contains bounding box also. Keywords are:
\verbatim
ORGANIZATION
DIGIT DATE
DIGIT NAME
MAP NAME
MAP DATE
MAP SCALE
OTHER INFO
ZONE
WEST EDGE
EAST EDGE
SOUTH EDGE
NORTH EDGE
MAP THRESH
\endverbatim
Example:
\verbatim
ORGANIZATION: NC OneMap
DIGIT DATE:
DIGIT NAME: helena
MAP NAME: North Carolina selected bridges (points map)
MAP DATE: Mon Nov 6 15:32:39 2006
MAP SCALE: 1
OTHER INFO:
ZONE: 0
MAP THRESH: 0.000000
\endverbatim
The body begins with the row:
\verbatim
VERTI:
\endverbatim
followed by records of primitives:
\verbatim
TYPE NUMBER_OF_COORDINATES [NUMBER_OF_CATEGORIES]
X Y [Z]
....
X Y [Z]
[ LAYER CATEGORY]
....
[ LAYER CATEGORY]
\endverbatim
Everything above in <tt>[]</tt> 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 vectors 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
\verbatim
X Y [Z]
\endverbatim
Note: The points are stored as y, x (i.e., east, north), which is the
reserve of the way GRASS usually represents geographic coordinates.
Example:
\verbatim
P 1 1
375171.4992779 317756.72097616
1 1
B 5
637740 219580
639530 219580
639530 221230
637740 221230
637740 219580
C 1 1
638635 220405
1 2
\endverbatim
In this example, the first vector feature is a point with category
number 1. The second vector feature is a boundary composed by 5
points. The third feature is a centroid with category number 2. The
boundary and the centroid form an area with category number 2. All
vector feature mentioned above are located in layer 1.
*/
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