added not on using LINE AREA or PRINT

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@2148 a5681a0c-68f1-0310-ab6d-d61299d08faa

diff --git a/doc/rrdgraph.pod b/doc/rrdgraph.pod
index ca3c128..be421e8 100644 (file)
--- a/doc/rrdgraph.pod
+++ b/doc/rrdgraph.pod
@@ -485,8 +485,9 @@ B<CDEF:>I<vname>B<=>I<RPN expression>
 
 B<VDEF:>I<vname>B<=>I<RPN expression>
 
-You need at least one B<DEF> statement to generate anything. The
-other statements are useful but optional.
+You need at least one B<DEF> and one B<LINE>, B<AREA>, B<GPRINT>, B<PRINT>
+statement to generate anything useful.
+
 See L<rrdgraph_data> and L<rrdgraph_rpn> for the exact format.
 
 NOTE: B<Graph and print elements>