diff --git a/chart.module b/chart.module
index 2e6da2d..5a3e374 100644
--- a/chart.module
+++ b/chart.module
@@ -72,6 +72,13 @@ define('CHART_LEGEND_TOP_VERTICAL', 'tv');
 define('CHART_LEGEND_RIGHT', 'r');
 define('CHART_LEGEND_LEFT', 'l');

+/**
+ * Bar Width and Spacing
+ */
+define('CHART_ABSOLUTE_SPACING', 'a');
+define('CHART_RELATIVE_SPACING', 'r');
+
+
 /*-----------------------------------------------------------------
  * Hook Implementations
  *------------------------------------------------------------------*/
@@ -236,8 +243,8 @@ function chart_copy($chart, $name = NULL, $dest = 'charts', $replace = FILE_EXIS
  *   - #mixed_axis_labels: (chxt) (Optional) An array of mixed axis labels.
  *   - #mixed_axis_label_styles: (chxs) (Optional) An array of mixed axis label
  *       styles.
- *   - #bar_size: (chbh) (Optional) 'a' for automatic, 'r' for relative, or an
-         array using keys: #size and #spacing.
+ *   - #bar_size: (chbh) (Optional) A string or an array using keys: #size,
+ *       #spacing, $group_spacing.
  *   - #countries: (chld) (Optional) An array of countries.
  *   - #georange: (chtm) (Optional) The geographical scope.
  *
@@ -594,7 +601,7 @@ function _chart_append($attr, $value, &$data) {
         $data[$attr] .= $value;
       }
       else {
-        $data[$attr] .= implode(',', array($value['#size'], $value['#spacing']));
+        $data[$attr] .= implode(',', array($value['#size'], $value['#spacing'], $value['#group_spacing']));
       }
       break;

@@ -1084,12 +1091,16 @@ function chart_range_marker($start, $end, $virtical = TRUE, $color = '000000') {
  * @param int $spacing
  *   (optional) Pixel spacing between bars.
  *
+ * @param int $group_spacing
+ *   (optional) Pixel spacing between bars.
+ *
  * @return array
  */
-function chart_bar_size($size = 40, $spacing = 20) {
+function chart_bar_size($size = 40, $spacing = 20, $group_spacing = 30) {
   return array(
     '#size'    => $size,
     '#spacing' => $spacing,
+    '#group_spacing' => $group_spacing,
   );
 }