update to include behavior for 3D and also note this seems to go beyond what the...

git-svn-id: http://svn.osgeo.org/postgis/trunk@4098 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/doc/reference.xml b/doc/reference.xml
index ec63081be42240b69180849c2b421c2e6d88105b..976ac608c4b2984e71dcdc4cef1ea66947f945b8 100644 (file)
--- a/doc/reference.xml
+++ b/doc/reference.xml
@@ -11007,7 +11007,17 @@ st_perimeter
                          <imagedata fileref="images/check.png" />
                        </imageobject>
                  </inlinemediaobject> This method implements the SQL/MM
-               specification: SQL-MM 3: 8.1.5, 9.5.6</para>
+               specification: SQL-MM 3: 8.1.5, 9.5.6.
+            According to the specs, ST_PointOnSurface works for surface geometries (POLYGONs, MULTIPOLYGONS, CURVED POLYGONS).  So PostGIS seems to be extending what
+                the spec allows here.  Most databases Oracle,DB II, ESRI SDE seem to only support this function for surfaces.  SQL Server 2008 like PostGIS supports for all common geometries.
+       </para>
+               
+                       <!-- Optionally mention 3d support -->
+    <para><inlinemediaobject>
+        <imageobject>
+          <imagedata fileref="images/check.png" />
+        </imageobject>
+      </inlinemediaobject> This function supports 3d (only for POINT,MULTIPOINT, LINESTRING, MULTILINESTRING) and will not drop the z-index.</para>
          </refsection>
 
          <refsection>
@@ -11029,7 +11039,14 @@ SELECT ST_AsText(ST_PointOnSurface('POLYGON((0 0, 0 5, 5 5, 5 0, 0 0))'::geometr
    st_astext
 ----------------
  POINT(2.5 2.5)
-(1 row)</programlisting>
+(1 row)
+
+SELECT ST_AsEWKT(ST_PointOnSurface(ST_GeomFromEWKT('LINESTRING(0 5 1, 0 0 1, 0 10 2)')));
+   st_asewkt
+----------------
+ POINT(0 0 1)
+(1 row)
+</programlisting>
          </refsection>
 
          <refsection>