add note on variable names

[rrdtool.git] / doc / rrdgraph_data.pod

diff --git a/doc/rrdgraph_data.pod b/doc/rrdgraph_data.pod
index 5b71c87..c57b2c3 100644 (file)
--- a/doc/rrdgraph_data.pod
+++ b/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, -,_> with 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>>]
@@ -27,7 +30,7 @@ This command fetches data from an B<RRD> file.  The virtual name
 I<vname> can then be used throughout the rest of the script. By
 default, an B<RRA> which contains the correct consolidated data
 at an appropriate resolution will be chosen.  The resolution can
-be overridden with the L<--step|rrdgraph/item_Time> option. 
+be overridden with the L<--step|rrdgraph/item_Time> option.
 The resolution can again be overridden by specifying the B<step size>.
 The time span of this data is the same as for the graph by default,
 you can override this by specifying B<start and end>.  Remember to