.. index::
   single: LAYER
    
.. _layer:

*****************************************************************************
 LAYER
*****************************************************************************

.. index::
   pair: LAYER; CLASS
    
:ref:`CLASS`
    Signals the start of a :ref:`CLASS` object.

    Inside a layer, only a single class will be used for the rendering
    of a feature. Each feature is tested against each class in the order
    in which they are defined in the mapfile. The first class that matches
    the its min/max scale constraints and its :ref:`EXPRESSION <expressions>`
    check for the current feature will be used for rendering.

.. index::
   pair: LAYER; CLASSGROUP
    
CLASSGROUP  [string]
    Specify the class's group that would be considered at rendering time.  
    The :ref:`CLASS` object's GROUP parameter must be used in combination with
    CLASSGROUP.
    
.. index::
   pair: LAYER; CLASSITEM
    
.. _CLASSITEM:

CLASSITEM [attribute]
    Item name in attribute table to use for class lookups.

.. index::
   pair: LAYER; CLUSTER
    
:ref:`CLUSTER`
    Signals the start of a :ref:`CLUSTER` object.

    The CLUSTER configuration option provides to combine multiple features from 
    the layer into single (aggregated) features based on their relative positions.
    Supported only for POINT layers.
    
    .. seealso::       
        :ref:`rfc69`
    
.. index::
   pair: LAYER; CONNECTION
    
CONNECTION [string]
    Database connection string to retrieve remote data.

    An SDE connection string consists of a hostname, instance name, 
    database name, username and password separated by commas.

    A PostGIS connection string is basically a regular PostgreSQL connection 
    string, it takes the form of 
    "user=nobody password=****** dbname=dbname host=localhost port=5432"

    An Oracle connection string: user/pass[@db]
    
    .. seealso::
        See :ref:`vector` for specific connection information for various
        data sources.

.. index::
   pair: LAYER; CONNECTIONTYPE
    
.. index::
   triple: LAYER; CONNECTIONTYPE; local
    
.. index::
   triple: LAYER; CONNECTIONTYPE; ogr
    
.. index::
   triple: LAYER; CONNECTIONTYPE; oraclespatial
    
.. index::
   triple: LAYER; CONNECTIONTYPE; plugin
    
.. index::
   triple: LAYER; CONNECTIONTYPE; postgis
    
.. index::
   triple: LAYER; CONNECTIONTYPE; sde
    
.. index::
   triple: LAYER; CONNECTIONTYPE; union
    
.. index::
   triple: LAYER; CONNECTIONTYPE; uvraster
    
.. index::
   triple: LAYER; CONNECTIONTYPE; wfs
    
.. index::
   triple: LAYER; CONNECTIONTYPE; wms
    
CONNECTIONTYPE [local|ogr|oraclespatial|plugin|postgis|sde|union|uvraster|wfs|wms]
    Type of connection. Default is local. See additional documentation for 
    any other type.

    .. seealso::
        See :ref:`vector` for specific connection information for various
        data sources.  See :ref:`union` for combining layers, added in MapServer
        6.0
        
    .. note::

        *mygis* is another connectiontype, but it is deprecated; please
        see the :ref:`MySQL section <mysql>` of the Vector Data document 
        for connection details.        

.. index::
   pair: LAYER; DATA
    
DATA [filename]|[sde parameters][postgis table/column][oracle table/column]
    Full filename of the spatial data to process. No file extension is 
    necessary for shapefiles. Can be specified relative to the 
    SHAPEPATH option from the Map Object.
    
    If this is an SDE layer, the parameter should include the name of 
    the layer as well as the geometry column, i.e. "mylayer,shape,myversion".
    
    If this is a PostGIS layer, the parameter should be in the form of 
    "<columnname> from <tablename>", where "columnname" is the name of the 
    column containing the geometry objects and "tablename" is the name of the 
    table from which the geometry data will be read.
    
    For Oracle, use "shape FROM table" or "shape FROM (SELECT statement)" or 
    even more complex Oracle compliant queries! Note that there are important 
    performance impacts when using spatial subqueries however. Try using 
    MapServer's FILTER_ whenever possible instead. You can also see the SQL 
    submitted by forcing an error, for instance by submitting a DATA parameter 
    you know won't work, using for example a bad column name.

    .. seealso::
        See :ref:`vector` for specific connection information for various
        data sources.

.. index::
   pair: LAYER; DEBUG
     
DEBUG [off|on|0|1|2|3|4|5]
    Enables debugging of a layer in the current map. 

    *Debugging with MapServer versions >= 5.0:*

    Verbose output is generated and sent to the standard error output (STDERR)
    or the MapServer errorfile if one is set using the "MS_ERRORFILE" environment
    variable.  You can set the environment variable by using the CONFIG parameter
    at the MAP level of the mapfile, such as:

    .. code-block:: mapfile

      CONFIG "MS_ERRORFILE" "/ms4w/tmp/ms_error.txt"

    You can also set the environment variable in Apache by adding the following
    to your httpd.conf:

    ::

      SetEnv MS_ERRORFILE "/ms4w/tmp/ms_error.txt"

    Once the environment variable is set, the DEBUG mapfile parameter can be
    used to control the level of debugging output.  Here is a description of the
    possible DEBUG values:

    - **DEBUG O or OFF** - only msSetError() calls are logged to MS_ERRORFILE. No
      msDebug() output at all. This is the default and corresponds to the
      original behavior of MS_ERRORFILE in MapServer 4.x

    - **DEBUG 1 or ON** - includes all output from DEBUG 0 plus msDebug() warnings
      about common pitfalls, failed assertions or non-fatal error situations
      (e.g. missing or invalid values for some parameters, missing shapefiles
      in tileindex, timeout error from remote WMS/WFS servers, etc.)

    - **DEBUG 2** - includes all output from DEBUG 1 plus notices and timing
      information useful for tuning mapfiles and applications

    - **DEBUG 3** - all of DEBUG 2 plus some debug output useful in
      troubleshooting problems such as WMS connection URLs being called,
      database connection calls, etc. This is the recommended level for
      debugging mapfiles.

    - **DEBUG 4** - DEBUG 3 plus even more details...

    - **DEBUG 5** - DEBUG 4 plus any msDebug() output that might be more useful to
      the developers than to the users.

    You can also set the debug level by using the "MS_DEBUGLEVEL" environment
    variable.

    The DEBUG setting can also be specified for the entire map, by setting the
    DEBUG parameter in the :ref:`MAP` object.

    For more details on this debugging mechanism, please see :ref:`RFC28`.

    *Debugging with MapServer versions < 5:*

    Verbose output is generated and sent to the standard error output (STDERR)
    or the MapServer logfile if one is set using the LOG parameter in the WEB
    object.  Apache users will see timing details for drawing in Apache's
    error_log file.  Requires MapServer to be built with the DEBUG=MSDEBUG
    option (--with-debug configure option).

.. index::
   pair: LAYER; DUMP
    
DUMP [true|false]
    Switch to allow MapServer to return data in GML format. Useful when 
    used with WMS GetFeatureInfo operations. "false" by default.

    .. deprecated:: 6.0 `LAYER` `METADATA` is used instead.

    .. seealso:: :ref:`WMS_SERVER`

.. index::
   pair: LAYER; EXTENT
    
EXTENT [minx] [miny] [maxx] [maxy]
    The spatial extent of the data. In most cases you will not need 
    to specify this, but it can be used to avoid the speed cost of having 
    MapServer compute the extents of the data.  An application can also
    possibly use this value to override the extents of the map.

.. index::
   pair: LAYER; FEATURE
    
:ref:`FEATURE`
    Signals the start of a :ref:`FEATURE` object.

.. index::
   pair: LAYER; FILTER
    
.. _FILTER:
    
FILTER [string]
    This parameter allows for data specific attribute filtering that is done 
    at the same time spatial filtering is done, but before any CLASS 
    expressions are evaluated. For OGR and shapefiles the string is simply 
    a mapserver regular expression. For spatial databases the string is a 
    SQL WHERE clause that is valid with respect to the underlying database.

    For example: FILTER ([type]='road' and [size]<2)

.. index::
   pair: LAYER; FILTERITEM
    
FILTERITEM [attribute]
    Item to use with simple FILTER_ expressions. OGR and shapefiles only.

.. index::
   pair: LAYER; FOOTER
    
FOOTER [filename]
    Template to use *after* a layer's set of results have been sent. 
    Multiresult query modes only.

.. index::
   pair: LAYER; GRID
    
:ref:`GRID`
    Signals the start of a :ref:`GRID` object.

.. index::
   pair: LAYER; GROUP
    
GROUP [name]
    Name of a group that this layer belongs to. The group name can then be 
    reference as a regular layer name in the template files, allowing to do 
    things like turning on and off a group of layers at once.

    If a group name is present in the LAYERS parameter of a CGI
    request, all the layers of the group are returned (the `STATUS` of
    the `LAYER`\s have no effect).

.. index::
   pair: LAYER; HEADER
    
HEADER [filename]
    Template to use *before* a layer's set of results have been sent. 
    Multiresult query modes only.

.. index::
   pair: LAYER; JOIN
    
:ref:`JOIN`
    Signals the start of a :ref:`JOIN` object.

LABELANGLEITEM [attribute]
    (As of MapServer 5.0 this parameter is no longer available.  Please see
    the :ref:`LABEL` object's ANGLE parameter)
    For MapServer versions < 5.0, this is the item name in attribute table 
    to use for class annotation angles. Values should be in degrees.
    
    .. deprecated:: 5.0

.. index::
   pair: LAYER; LABELCACHE
    
LABELCACHE [on|off]
    Specifies whether labels should be drawn as the features for this layer 
    are drawn, or whether they should be cached and drawn after all layers 
    have been drawn. Default is on. Label overlap removal, auto placement 
    etc... are only available when the label cache is active.

.. index::
   pair: LAYER; LABELITEM
    
LABELITEM [attribute]
    Item name in attribute table to use for class annotation (i.e. labeling).

.. index::
   pair: LAYER; LABELMAXSCALEDENOM

LABELMAXSCALEDENOM [double]
    Minimum scale at which this LAYER is labeled.  Scale is given as the
    denominator of the actual scale fraction, for example for a map at a scale
    of 1:24,000 use 24000.  Implemented in MapServer 5.0, to replace the
    deprecated LABELMAXSCALE parameter.

    .. seealso::
        
        :term:`Map Scale`

LABELMAXSCALE [double] - deprecated
    Since MapServer 5.0 the proper parameter to use is LABELMAXSCALEDENOM
    instead.  The deprecated LABELMAXSCALE is the minimum scale at which this
    LAYER is labeled.  Scale is given as the denominator of the actual scale
    fraction, for example for a map at a scale of 1:24,000 use 24000.
    
    .. deprecated:: 5.0

.. index::
   pair: LAYER; LABELMINSCALEDENOM

LABELMINSCALEDENOM [double]
    Maximum scale at which this LAYER is labeled.  Scale is given as the
    denominator of the actual scale fraction, for example for a map at a scale
    of 1:24,000 use 24000.  Implemented in MapServer 5.0, to replace the
    deprecated LABELMINSCALE parameter.

    .. seealso::
        
        :term:`Map Scale`

LABELMINSCALE [double] - deprecated
    Since MapServer 5.0 the proper parameter to use is LABELMINSCALEDENOM
    instead.  The deprecated LABELMINSCALE is the maximum scale at which this
    LAYER is labeled.  Scale is given as the denominator of the actual scale
    fraction, for example for a map at a scale of 1:24,000 use 24000.

    .. deprecated:: 5.0

.. index::
   pair: LAYER; LABELREQUIRES
    
.. _LABELREQUIRES:

LABELREQUIRES [expression]
    Sets context for labeling this layer, for example:

    .. code-block:: mapfile
    
        LABELREQUIRES "![orthoquads]"

    means that this layer would NOT be labeled if a layer named 
    "orthoquads" is on. The expression consists of a boolean expression based 
    on the status of other layers, each [layer name] substring is replaced by 
    a 0 or a 1 depending on that layer's STATUS_ and then evaluated as normal. 
    Logical operators AND and OR can be used.

LABELSIZEITEM [attribute]
    (As of MapServer 5.0 this parameter is no longer available.  Please see
    the :ref:`LABEL` object's SIZE parameter)
    For MapServer versions < 5.0, this is the item name in attribute table to 
    use for class annotation sizes. Values should be in pixels.
    
    .. deprecated:: 5.0

.. index::
   pair: LAYER; MAXFEATURES
    
MAXFEATURES [integer]
    Specifies the number of features that should be drawn for this layer in 
    the CURRENT window. Has some interesting uses with annotation and with 
    sorted data (i.e. lakes by area).

.. index::
   pair: LAYER; MAXGEOWIDTH
    
MAXGEOWIDTH [double]
    Maximum width, in the map's geographic units, at which this LAYER is drawn.  
    If MAXSCALEDENOM is also specified then MAXSCALEDENOM will be used instead. 
    *(added in MapServer 5.4.0)*
    
    The width of a map in geographic units can be found by calculating the
    following from the extents::
    
      [maxx] - [minx]    

.. index::
   pair: LAYER; MAXSCALEDENOM
    
MAXSCALEDENOM [double]
    Minimum scale at which this LAYER is drawn.  Scale is given as the
    denominator of the actual scale fraction, for example for a map at a scale
    of 1:24,000 use 24000.  Implemented in MapServer 5.0, to replace the
    deprecated MAXSCALE parameter.

    .. seealso::
        
        :term:`Map Scale`

MAXSCALE [double] - deprecated
    Since MapServer 5.0 the proper parameter to use is MAXSCALEDENOM instead.
    The deprecated MAXSCALE is the minimum scale at which this LAYER is drawn.  
    Scale is given as the denominator of the actual scale fraction, for example
    for a map at a scale of 1:24,000 use 24000.

    .. deprecated:: 5.0

.. index::
   pair: LAYER; METADATA
    
METADATA
    This keyword allows for arbitrary data to be stored as name value pairs.
    This is used with :ref:`OGC WMS <wms_server>` to define things such as
    layer title. It can also allow more flexibility in creating templates, as
    anything you put in here will be accessible via template tags.

    Example:
    
    .. code-block:: mapfile
    
        METADATA
            "title" "My layer title"
            "author" "Me!"
        END

.. index::
    pair: LAYER; MINGEOWIDTH

MINGEOWIDTH [double]
    Minimum width, in the map's geographic units, at which this LAYER is drawn.  
    If MINSCALEDENOM is also specified then MINSCALEDENOM will be used instead. 
    *(added in MapServer 5.4.0)*   
    
    The width of a map in geographic units can be found by calculating the
    following from the extents::
    
      [maxx] - [minx]      

.. index::
   pair: LAYER; MINSCALEDENOM
    
MINSCALEDENOM [double]
    Maximum scale at which this LAYER is drawn.  Scale is given as the
    denominator of the actual scale fraction, for example for a map at a scale
    of 1:24,000 use 24000.  Implemented in MapServer 5.0, to replace the
    deprecated MINSCALE parameter.

    .. seealso::
        
        :term:`Map Scale`

MINSCALE [double] - deprecated
    Since MapServer 5.0 the proper parameter to use is MINSCALEDENOM
    instead.  The deprecated MINSCALE is the maximum scale at which this LAYER
    is drawn.  Scale is given as the denominator of the actual scale fraction,
    for example for a map at a scale of 1:24,000 use 24000.

    .. deprecated:: 5.0

.. index::
   pair: LAYER; NAME
    
NAME [string]
    Short name for this layer. This name is the link between the
    mapfile and web interfaces that refer to this name. They must be
    identical. The name should be unique, unless one layer replaces
    another at different scales. Use the GROUP option to associate
    layers with each other.  It is recommended that the name not
    contain spaces, special characters, or begin with a number (which
    could cause problems through interfaces such as OGC services).

.. index::
   pair: LAYER; OFFSITE
    
OFFSITE [r] [g] [b]
    Sets the color index to treat as transparent for raster layers.

.. index::
   pair: LAYER; OPACITY
    
.. _OPACITY:

OPACITY [integer|alpha]
    Sets the opacity level (or the inability to see through the layer) of all
    classed pixels for a given layer. The value can either be an integer in the
    range (0-100) or the named symbol "ALPHA". A value of 100 is opaque and 
    0 is fully transparent.  Implemented in MapServer 5.0, to replace the
    deprecated TRANSPARENCY parameter.

    The "ALPHA" symbol directs the MapServer rendering code to honor the 
    indexed or alpha transparency of pixmap symbols used to style a layer. 
    This is only needed in the case of RGB output formats, and should be used 
    only when necessary as it is expensive to render transparent pixmap 
    symbols onto an RGB map image.
    
.. index::
   pair: LAYER; PLUGIN
    
PLUGIN [filename]
    Additional library to load by MapServer, for this layer.  This is commonly
    used to load specific support for SDE and Microsoft SQL Server layers, 
    such as:
    
      .. code-block:: mapfile

        CONNECTIONTYPE PLUGIN
        CONNECTION "hostname,port:xxx,database,username,password"
        PLUGIN "C:/ms4w/Apache/specialplugins/msplugin_sde_92.dll"  
        DATA "layername,geometrycolumn,SDE.DEFAULT"      

.. index::
   pair: LAYER; POSTLABELCACHE
    
POSTLABELCACHE [true|false]
    Tells MapServer to render this layer after all labels in the cache have 
    been drawn. Useful for adding neatlines and similar elements. 
    Default is false.

.. index::
   pair: LAYER; PROCESSING
    
.. index:: PROCESSING, Raster options, Special options

PROCESSING [string]
    Passes a processing directive to be used with this layer. The supported 
    processing directives vary by layer type, and the underlying driver that 
    processes them. 
     
    .. index::
       triple: LAYER; PROCESSING; ITEMS

    - **Attributes Directive** - The ITEMS processing option allows to 
      specify the name of attributes for inline layers or specify the subset 
      of the attributes to be used by the layer, such as:
    
      .. code-block:: mapfile

          PROCESSING "ITEMS=itemname1,itemname2,itemname3"

    .. index::
       triple: LAYER; PROCESSING; CLOSE_CONNECTION

    - **Connection Pooling Directive** - This is where you can enable 
      connection pooling for certain layer layer types. Connection pooling 
      will allow MapServer to share the handle to an open database or layer 
      connection throughout a single map draw process. Additionally, if you 
      have FastCGI enabled, the connection handle will stay open indefinitely, 
      or according to the options specified in the
      :ref:`FastCGI <fastcgi>` configuration. :ref:`oci`, :ref:`arcsde`,
      :ref:`ogr` and :ref:`input_postgis` currently support this approach.

      .. code-block:: mapfile

          PROCESSING "CLOSE_CONNECTION=DEFER"
          
    .. index::
       triple: LAYER; PROCESSING; LABEL_NO_CLIP

    - **Label Directive** - The LABEL_NO_CLIP processing option can be
      used to skip clipping of shapes when determining associated
      label anchor points. This avoids changes in label position as
      extents change between map draws. It also avoids duplicate
      labels where features appear in multiple adjacent tiles when
      creating tiled maps.

      .. code-block:: mapfile

          PROCESSING "LABEL_NO_CLIP=True"

    .. index::
       triple: LAYER; PROCESSING; GETSHAPE_STYLE_ITEMS

    - **OGR Styles Directive** - This directive can be used for obtaining
      label styles through MapScript.  For more information see the 
      :ref:`MapServer's OGR document <styleitemauto-label-styles>`.
      
      .. code-block:: mapfile

          PROCESSING "GETSHAPE_STYLE_ITEMS=all"
          
    .. index::
       triple: LAYER; PROCESSING; raster options

    - **Raster Directives** - All raster processing options are described 
      in :ref:`raster`.  Here we see the SCALE and BANDs directives used to
      autoscale raster data and alter the band mapping.  

      .. code-block:: mapfile
    
          PROCESSING "SCALE=AUTO"
          PROCESSING "BANDS=3,2,1"

.. index::
   pair: LAYER; PROJECTION
    
:ref:`PROJECTION`
    Signals the start of a :ref:`PROJECTION` object.

.. index::
   pair: LAYER; REQUIRES
    
REQUIRES [expression]
    Sets context for displaying this layer (see LABELREQUIRES_).

.. index::
   pair: LAYER; SIZEUNITS
    
.. index::
   triple: LAYER; SIZEUNITS; feet
    
.. index::
   triple: LAYER; SIZEUNITS; inches
    
.. index::
   triple: LAYER; SIZEUNITS; kilometers
    
.. index::
   triple: LAYER; SIZEUNITS; meters
    
.. index::
   triple: LAYER; SIZEUNITS; miles
    
.. index::
   triple: LAYER; SIZEUNITS; nauticalmiles
    
.. index::
   triple: LAYER; SIZEUNITS; pixels
    
SIZEUNITS [feet|inches|kilometers|meters|miles|nauticalmiles|pixels]
    Sets the unit of :ref:`CLASS` object SIZE values (default is pixels). 
    Useful for simulating buffering. `Nauticalmiles` was added in MapServer 5.6.

.. index::
   pair: LAYER; STATUS
    
.. _STATUS:

STATUS [on|off|default]
    Sets the current status of the layer. Often modified by MapServer itself. 
    Default turns the layer on permanently.
    
    .. note::
        
        In :ref:`CGI <cgi>` mode, layers with STATUS DEFAULT cannot be turned
        off using normal mechanisms. It is recommended to set layers to STATUS
        DEFAULT while debugging a problem, but set them back to ON/OFF in
        normal use.
    
    .. note::

        For :ref:`WMS <wms_server>`, layers in the server mapfile with STATUS
        DEFAULT are always sent to the client.

    .. note::
       The STATUS of the individual layers of a GROUP has no effect
       when the group name is present in the LAYERS parameter of a CGI
       request - all the layers of the group will be returned.

.. index::
   pair: LAYER; STYLEITEM
    
STYLEITEM [<attribute>|auto]
    Item to use for feature specific styling. The style information may be 
    represented by a separate attribute (style string) attached to the feature.
    MapServer supports the following style string representations:
    
    - **MapServer STYLE definition** - The style string can be represented as a 
      MapServer :ref:`STYLE` block according to the following example:
    
      .. code-block:: mapfile

          STYLE BACKGROUNDCOLOR 128 0 0 COLOR 0 0 208 END

    - **MapServer CLASS definition** - By specifying the entire :ref:`CLASS` 
      instead of a single style allows to use further options (like setting 
      expressions, label attributes, multiple styles) on a per feature basis.

    - **OGR Style String** - MapServer support rendering the OGR style
      string format according to the `OGR - Feature Style
      Specification`_ documentation.  Currently only a few data
      sources support storing the styles along with the features (like
      MapInfo, AutoCAD DXF, Microstation DGN), however those styles
      can easily be transferred to many other data sources as a
      separate attribute by using the `ogr2ogr`_ command line tool as
      follows::

          ogr2ogr -sql "select *, OGR_STYLE from srclayer" "dstlayer" "srclayer"      
      
    .. index::
       triple: LAYER; STYLEITEM; AUTO
    
    The value: `AUTO` can be used for automatic styling.

    - Automatic styling can be provided by the driver. Currently, only
      the OGR driver supports automatic styling.

    - When used for a :ref:`union`, the styles from the source layers
      will be used.

.. index::
   pair: LAYER; SYMBOLSCALEDENOM
    
.. _SYMBOLSCALEDENOM:

SYMBOLSCALEDENOM [double]
    The scale at which symbols and/or text appear full size. This allows for
    dynamic scaling of objects based on the scale of the map. If not set then
    this layer will always appear at the same size. Scaling only takes place
    within the limits of MINSIZE and MAXSIZE as described above.  Scale is given
    as the denominator of the actual scale fraction, for example for a map at a
    scale of 1:24,000 use 24000.  Implemented in MapServer 5.0, to replace the
    deprecated SYMBOLSCALE parameter.

    .. seealso::
        
        :term:`Map Scale`

SYMBOLSCALE [double] - deprecated
    Since MapServer 5.0 the proper parameter to use is SYMBOLSCALEDENOM
    instead.  The deprecated SYMBOLSCALE is the scale at which symbols and/or
    text appear full size. This allows for dynamic scaling of objects based on
    the scale of the map. If not set then this layer will always appear at the
    same size. Scaling only takes place within the limits of MINSIZE and MAXSIZE
    as described above.  Scale is given as the denominator of the actual scale
    fraction, for example for a map at a scale of 1:24,000 use 24000.

    .. deprecated:: 5.0

.. index::
   pair: LAYER; TEMPLATE
    
:ref:`TEMPLATE <template>` [file|url]
    Used as a global alternative to :ref:`CLASS` `TEMPLATE`.
    See :ref:`template` for more info.

.. index::
   pair: LAYER; TILEINDEX
    
:ref:`TILEINDEX <tileindex>` [filename|layername]
    Name of the tileindex file or layer.  A tileindex is similar to 
    an ArcInfo library index.  The tileindex contains polygon features for 
    each tile. The item that contains the location of the tiled data is given 
    using the TILEITEM parameter.  When a file is used as the tileindex for
    shapefile or raster layers, the tileindex should be a shapefile.  For
    CONNECTIONTYPE OGR layers, any OGR supported datasource can be a
    tileindex.  Normally the location should contain the path to the tile
    file relative to the shapepath, not relative to the tileindex itself.    
    If the DATA parameter contains a value then it is added to the end of
    the location.  When a tileindex layer is used, it works similarly to 
    directly referring to a file, but any supported feature source can
    be used (ie. postgres, oracle).

    .. note::
    
        All files in the tileindex should have the same coordinate system, and
        for vector files the same set of attributes in the same order.

.. index::
   pair: LAYER; TILEITEM
    
TILEITEM [attribute]
    Item that contains the location of an individual tile, default is 
    "location".

.. index::
   pair: LAYER; TOLERANCE
    
.. _TOLERANCE:

TOLERANCE [double]
    Sensitivity for point based queries (i.e. via mouse and/or map 
    coordinates). Given in TOLERANCEUNITS. If the layer is a POINT or a LINE, 
    the default is 3. For all other layer types, the default is 0.  To 
    restrict polygon searches so that the point must occur in the polygon 
    set the tolerance to zero.

.. index::
   pair: LAYER; TOLERANCEUNITS
    
TOLERANCEUNITS [pixels|feet|inches|kilometers|meters|miles|nauticalmiles|dd]
    Units of the TOLERANCE value. Default is pixels. 
    `Nauticalmiles` was added in MapServer 5.6.

TRANSPARENCY [integer|alpha] - deprecated
    Since MapServer 5.0 the proper parameter to use is OPACITY.  The
    deprecated TRANSPARENCY parameter sets the transparency level of all classed
    pixels for a given layer.   The value can either be an integer in the range
    (0-100) or the named symbol "ALPHA". Although this parameter is named
    "transparency", the integer values actually parameterize layer opacity. A
    value of 100 is opaque and 0 is fully transparent.

    The "ALPHA" symbol directs the MapServer rendering code to honor the 
    indexed or alpha transparency of pixmap symbols used to style a layer. 
    This is only needed in the case of RGB output formats, and should be used 
    only when necessary as it is expensive to render transparent pixmap 
    symbols onto an RGB map image.

    .. deprecated:: 5.0

    .. seealso::
        
        :ref:`OPACITY <opacity>`
        
.. index::
   pair: LAYER; TRANSFORM
    
TRANSFORM [true|false ul|uc|ur|lc|cc|lr|ll|lc|lr]
    Tells MapServer whether or not a particular layer needs to be transformed 
    from some coordinate system to image coordinates. Default is true. This 
    allows you to create shapefiles in image/graphics coordinates and 
    therefore have features that will always be displayed in the same location 
    on every map. Ideal for placing logos or text in maps. Remember that the 
    graphics coordinate system has an origin in the upper left hand corner of 
    the image, contrary to most map coordinate systems.

    Version 4.10 introduces the ability to define features with coordinates
    given in pixels (or percentages, see UNITS), most often inline features,
    relative to something other than the UL corner of an image. That is what 
    'TRANSFORM FALSE' means. By setting an alternative origin it allows you
    to anchor something like a copyright statement to another portion of the
    image in a way that is independent of image size.

.. index::
   pair: LAYER; TYPE
    
.. index::
   triple: LAYER; TYPE; annotation
    
.. index::
   triple: LAYER; TYPE; chart
    
.. index::
   triple: LAYER; TYPE; circle
    
.. index::
   triple: LAYER; TYPE; line
    
.. index::
   triple: LAYER; TYPE; point
    
.. index::
   triple: LAYER; TYPE; polygon
    
.. index::
   triple: LAYER; TYPE; raster
    
.. index::
   triple: LAYER; TYPE; query
    
TYPE [annotation|chart|circle|line|point|polygon|raster|query]
    Specifies how the data should be drawn. Need not be the same as the 
    shapefile type. For example, a polygon shapefile may be drawn as a point 
    layer, but a point shapefile may not be drawn as a polygon layer. Common 
    sense rules. Annotation means that a label point will be calculated for 
    the features, but the feature itself will not be drawn although a marker 
    symbol can be optionally drawn. this allows for advanced labeling like 
    numbered highway shields. Points are labeled at that point. Polygons are 
    labeled first using a centroid, and if that doesn't fall in the polygon a 
    scanline approach is used to guarantee the label falls within the feature. 
    Lines are labeled at the middle of the longest arc in the visible portion 
    of the line. Query only means the layer can be queried but not drawn.

    In order to differentiate between POLYGONs and POLYLINEs (which do not 
    exist as a type), simply respectively use or omit the COLOR keyword when 
    classifying. If you use it, it's a polygon with a fill color, otherwise 
    it's a polyline with only an OUTLINECOLOR.

    

    A circle must be defined by a a minimum bounding rectangle. That is, two
    points that define the smallest square that can contain it. These two points 
    are the two opposite corners of said box.

    The following is an example using inline points to draw a circle:

    .. code-block:: mapfile
      
      LAYER
        NAME 'inline_circles'
        TYPE CIRCLE
        STATUS ON
        FEATURE
          POINTS
            74.01 -53.8
            110.7 -22.16
          END
        END  
        CLASS
          STYLE
            COLOR 0 0 255
          END
        END
      END

    .. seealso::
        
        For CHART layers, see the :ref:`Dynamic Charting<dynamic_charting>`
        HowTo.

.. index::
   pair: LAYER; UNITS
    
.. index::
   triple: LAYER; UNITS; dd
    
.. index::
   triple: LAYER; UNITS; feet
    
.. index::
   triple: LAYER; UNITS; inches
    
.. index::
   triple: LAYER; UNITS; kilometers
    
.. index::
   triple: LAYER; UNITS; meters
    
.. index::
   triple: LAYER; UNITS; miles
    
.. index::
   triple: LAYER; UNITS; nauticalmiles
    
.. index::
   triple: LAYER; UNITS; percentages
    
.. index::
   triple: LAYER; UNITS; pixels
    
UNITS [dd|feet|inches|kilometers|meters|miles|nauticalmiles|percentages|pixels]
    Units of the layer.  `percentages` (in this case a value between 0
    and 1) was added in MapServer 4.10 and is mostly geared for inline
    features.  `nauticalmiles` was added in MapServer 5.6.

.. index::
   pair: LAYER; VALIDATION
    
VALIDATION
    Signals the start of a `VALIDATION` block.

    As of MapServer 5.4.0, `VALIDATION` blocks are the preferred
    mechanism for specifying validation patterns for CGI param runtime
    substitutions.  See :ref:`RUNSUB`.

.. _`OGR - Feature Style Specification`: http://www.gdal.org/ogr/ogr_feature_style.html
.. _`ogr2ogr`: http://www.gdal.org/ogr2ogr.html