X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=doc%2Frrdgraph_data.pod;h=6c8b28a159b2732682610af1e3d680dcdb822fae;hb=f8c81c20d9fe8183cb481944cd9b29ace3ee37aa;hp=64c559aba27f36485883ea513484487a46cdc112;hpb=342b22c3e74a10d7049285c2cea7383676bcfc95;p=rrdtool.git

diff --git a/doc/rrdgraph_data.pod b/doc/rrdgraph_data.pod
index 64c559a..6c8b28a 100644
--- a/doc/rrdgraph_data.pod
+++ b/doc/rrdgraph_data.pod
@@ -22,6 +22,10 @@ own manual page.
 Variable names (I<vname>) must be made up strings of the following characters
 C<A-Z, a-z, 0-9, -,_> and a maximum length of 255 characters.
 
+When picking variable names, make sure you do not choose a name that is
+already taken by an RPN operator. A save bet it to use lowercase or
+mixedcase names for variables since operators will always be in uppercase.
+
 =head1 DEF
 
 B<DEF:>I<E<lt>vnameE<gt>>=I<E<lt>rrdfileE<gt>>:I<E<lt>ds-nameE<gt>>:I<E<lt>CFE<gt>>[:step=I<E<lt>stepE<gt>>][:start=I<E<lt>timeE<gt>>][:end=I<E<lt>timeE<gt>>][:reduce=I<E<lt>B<CF>E<gt>>]