Note that ST_Intersection drops M

References #3826 for PostGIS 2.4.0

git-svn-id: http://svn.osgeo.org/postgis/trunk@15611 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/doc/reference_processing.xml b/doc/reference_processing.xml
index bea92fc5948f5bc4ade3e77e46ea10913e8fc9cf..dcd0384ee153054f5e47c60e2a87c9c0dedbd7d1 100644 (file)
--- a/doc/reference_processing.xml
+++ b/doc/reference_processing.xml
@@ -1810,6 +1810,8 @@ Returns a geometry that represents the shared portion of geomA and geomB.
                        <para>Do not call with a <varname>GEOMETRYCOLLECTION</varname> as an argument</para>
                  </important>
 
+               <warning><para>This function will drop the M coorindate values if present.</para></warning>
+
                  <warning><para>If working with 3D geometries, you may want to use SFGCAL based <xref linkend="ST_3DIntersection" /> which does a proper 3D intersection for 3D geometries.  Although this function works with Z-coordinate, it does an averaging of Z-Coordinate values when <code>postgis.backend=geos</code>. <code>postgis.backend=sfcgal</code>, it will return a 2D geometry regardless ignoring the Z-Coordinate. Refer to <xref linkend="postgis_backend" /> for details.</para></warning>
 
                  <para>Performed by the GEOS module</para>