added notes about VDEF expressions not being general purpose

[rrdtool.git] / doc / rrdgraph_data.pod

diff --git a/doc/rrdgraph_data.pod b/doc/rrdgraph_data.pod
index c3891d4..04d9761 100644 (file)
--- a/doc/rrdgraph_data.pod
+++ b/doc/rrdgraph_data.pod
@@ -71,6 +71,9 @@ elements.
 
 Example: C<VDEF:avg=mydata,AVERAGE>
 
+Note that currently only agregation functions work in VDEF rpn expressions.
+Patches to change this are welcome.
+
 =head1 CDEF
 
 B<CDEF>:I<vname>=I<RPN expression>