MAPEXTENT {feature_class} <cover...cover>
MAPEXTENT <* | xmin ymin xmax ymax>
MAPEXTENT TILES {library...library}
MAPEXTENT IMAGE <image...image | image_catalog>
MAPEXTENT <geo_dataset...geo_dataset>
MAPEXTENT DXF <dxf...dxf>
 
specifies the coverage area to be shown on the map.
 
arguments
 
{feature_class} <cover...cover> - sets the MAPEXTENT from the minimum and
maximum x,y coordinates of the features in {feature_class} in one or more
coverages.
 
{feature_class} - specifies the class of features from <cover...cover> that
will be read to find the minimum and maximum x,y coordinates.  {feature_class}
is given as one of these keywords:
 
ANNO.subclass - for coverage annotation
ARC - for arc coverage features
LINK - for link coverage features
NODE - for node coverage features
POINT - for point coverage features
POLY - for polygon coverage features
ROUTE.subclass - for route coverage features
SECTIONS.subclass - for section coverage features
TICS - for coverage tics
 
If no {feature_class} is given, the MAPEXTENT is set from the BND file(s) of
<cover...cover> by default.
 
<cover...cover> - one or more coverages used to obtain the MAPEXTENT.  The
MAPEXTENT is set to the total geographic extent of the features in
{feature_class} from <cover...cover>.
 
<* | xmin ymin xmax ymax> - specifies the location of the MAPEXTENT.
 
* - specifies that the corner locations of the MAPEXTENT will be indicated with
the mode of interactive coordinate entry specified with the COORDINATE command.
Any two opposing corners may be entered in any order.  By default, the screen
cursor will be used.  To enter each corner point, position the cursor over the
desired point location and press any alphanumeric key.  (This method of setting
MAPEXTENT demands that MAPEXTENT has already been set using one of the other
methods).
 
xmin ymin xmax ymax - specifies the lower-left and upper-right corners of the
MAPEXTENT as minimum and maximum x,y map coordinates in MAPUNITS.  Use blank
spaces to separate the coordinate values in the list.
 
TILES {library...library} - sets the MAPEXTENT to be the area covered by the
currently selected tiles from currently selected map libraries.
 
TILES - keyword indicating that the extent be set from map library tiles.
 
{library...library} - the set of libraries from which to select tiles.  The
default is all map libraries set with the LIBRARY command.
 
IMAGE <image...image | image_catalog> - sets the map extent by using the
extremes of one or more images or an image catalog.  The map extent is defined
by transforming rows and columns into real-world coordinates.
 
IMAGE - keyword indicating that the extent be set from an image.
 
<image...image | image catalog> - name of the image(s) or image catalog.
 
<geo_dataset...geo_dataset> - specifies that the MAPEXTENT will be set to the
total geographic extent of one or more geographic data sets.  A valid data set
can be a coverage, a tin, a lattice or a grid.
 
DXF <dxf..dxf> - sets the MAPEXTENT by using the $EXTMIN and $EXTMAX values in
the header section of the dxf file or the coordinate values of the entities in
the ENTITIES section of the dxf file.
 
DXF - keyword indicating that the extent be set from a dxf file.
 
<dxf...dxf> - name of the dxf file(s).
 
notes
 
The simplest way to specify a map extent is to give the name of one or more
coverages that are to be represented on the map.  When several coverages are
named in MAPEXTENT, they do not have to be neighbors.  Whatever the position of
the coverages, MAPEXTENT makes the map area large enough to encompass them all.
 
Because there is no default MAPEXTENT, the command must be given before any
drawing can take place.  MAPEXTENT is, therefore, usually one of the first
commands used in a session.  MAPEXTENT can be respecified any number of times
during a session.
 
Naming a coverage in MAPEXTENT is simply a convenient way of specifying the
coordinate area for a map.  Once the map extent has been set, the map can
include features from any coverage covering some or all of the same coordinate
area, whether or not this coverage was named in MAPEXTENT.  So when you want to
make a map using features from several coverages that overlap one area (for
example, if your coverages represent different data layers for the same area),
you only have to name one of these coverages in MAPEXTENT to set the correct
map coordinate area.
 
If coverage features have been selected using RESELECT, ASELECT, NSELECT or
UNSELECT, the map extent is defined by the minimum and maximum x,y coordinates
of the features in the selected set for {feature_class}.
 
The map extent read from the {feature_class} is increased by
5 percent in the x- and y-dimensions.  This ensures that if the features are
drawn on the map, their symbols will fall inside the map extent and not be
graphically clipped.
 
The map extent is the coverage area covered by an ARCPLOT map.  The
CLIPMAPEXTENT command specifies whether the map extent area will be a graphic
clipping edge.  By default, any parts of coverage features that fall outside
this area are not drawn and are graphically clipped around the edge of the map
extent.  When CLIPMAPEXTENT is set to OFF, coverage features are drawn to the
edge of the map limits (if no MAPLIMITS has been specified, the coverage
features will be drawn to the edge of the available graphics page, the
PAGESIZE).
 
A map library must be selected with the LIBRARY command before MAPEXTENT can be
used with the TILES option.  TILES is used to select a set of tiles from a map
library that has been selected with the LIBRARY command.  By default, when the
LIBRARY command is used, all the tiles in the specified map library are
selected for use.  Reducing the set of tiles and reestablishing the map extent
is accomplished through combinations of the TILES and MAPEXTENT commands.
 
If the set of tiles is first reduced, the map extent can be adjusted to the
extent of the selected tiles; for example,
 
Arcplot: LIBRARY RDCOUNTY
Arcplot: TILES NW NE
Arcplot: MAPEXTENT TILES
Arcplot: POLYGONS .LANDUSE
 
The current set of tiles is reduced to NW and NE.  MAPEXTENT resets the
coverage area to the two named TILES from the selected map library.  The
POLYGONS command draws the polygon boundaries from the layer called LANDUSE
only for the two specified tiles with a map extent covering the area of these
two tiles plus
5 percent.
 
If the map extent is first adjusted, the set of currently selected tiles can be
set to those that fall at least partially within the current extent.  Any tile
that would not be seen on the screen would not be selected; for example,
 
Arcplot: LIBRARY RDCOUNTY
Arcplot: MAPEXTENT TILES
Arcplot: POLYGONS .NEIGHBORHOODS
Arcplot: MAPEXTENT *
Define the box
Arcplot: TILES MAPEXTENT
Arcplot: POLYGONS .LANDUSE
 
After setting the map extent based on visual reference (MAPEXTENT *), the set
of tiles is selected from those within the current map extent.  When the
POLYGON command draws polygon boundaries from the layer called LANDUSE, only
those tiles that could display will draw.
 
The set of polygon boundaries would not change if the TILES MAPEXTENT command
were not issued.  ARCPLOT would attempt to draw polygon boundaries for the
entire map library, since by default, all tiles are selected after the LIBRARY
command.  By reducing the number of tiles accessed through TILES MAPEXTENT, the
drawing time is reduced.  The more tiles within a library and the fewer tiles
within the map extent, the greater the savings in time with this technique.
 
MAPEXTENT with the IMAGE option can only be used with workstations or plotter
devices that support raster output (DISPLAY 9999 and 1040).
 
The map extent for an image is defined by the transformation parameters in the
world file, or if no world file exists, in the file header of the image itself.
If the header does not contain any transformation parameters, an identity
transformation is performed and the map extent is set to the number of rows and
columns in the image.
