diff --git a/lib/graphlib.php b/lib/graphlib.php
index c9daca47538..048b5b5cc01 100644
--- a/lib/graphlib.php
+++ b/lib/graphlib.php
@@ -143,7 +143,8 @@ class graph {
     'thousand_sep'       => ',',           // symbol for thousand separation ',' or ''
 
   );
-
+  var $y_tick_labels     =   null;         // array of text values for y-axis tick labels
+  var $offset_relation   =   null;         // array of offsets for different sets of data
 
 
     // init all text - title, labels, and axis text.