X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;f=program%2Fdoc%2Frrdgraph_data.pod;h=c3891d467bbbb240be5f2a5bb03363e99ea980b6;hb=40bf5441006c8924dcd46bd7edbbcbf85b8b377b;hp=e8b2c6719d3ecebb658bc0bd72c059b9745d2f7d;hpb=0a5c76d18a14d6d6714fa75022180d4e2da556ef;p=rrdtool-all.git

diff --git a/program/doc/rrdgraph_data.pod b/program/doc/rrdgraph_data.pod
index e8b2c671..c3891d46 100644
--- a/program/doc/rrdgraph_data.pod
+++ b/program/doc/rrdgraph_data.pod
@@ -19,6 +19,9 @@ useful information such as maximum, minimum etcetera. Two of the
 instructions use a language called B<RPN> which is described in its
 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.
+
 =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>>]