Attempt to clarify MULTIPOLYGON behavior in ST_SimplifyPreserveTopology (#240)

git-svn-id: http://svn.osgeo.org/postgis/trunk@4857 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/doc/reference.xml b/doc/reference.xml
index b6d95b53d0ef45a2af2d2cc5e46113be8d1b3621..83db485e2a601e20ede92275c7e1561e57c8c89e 100644 (file)
--- a/doc/reference.xml
+++ b/doc/reference.xml
@@ -13779,10 +13779,10 @@ FROM (SELECT ST_Buffer('POINT(1 3)', 10,12) As the_geom) As foo;
                <para>Returns a "simplified" version of the given geometry using
                        the Douglas-Peuker algorithm. Will avoid creating derived
                        geometries (polygons in particular) that are invalid. Will actually do something only with
-                               (multi)lines and (multi)polygons but you can safely call it with
-                               any kind of geometry. Since simplification occurs on a
-                               object-by-object basis you can also feed a GeometryCollection to
-                               this function.</para>
+                       (multi)lines and (multi)polygons but you can safely call it with
+                       any kind of geometry. Output polygons and multipolygons will be no more
+                       invalid than the inputs (that is, if the inputs have self-intersections, 
+                       this routine won't remove them, but neither will it introduce new ones).</para>
 
                <para>Performed by the GEOS module.</para>
                <note><para>Requires GEOS 3.0.0+</para></note>