Approval.

hi/measurement_type_set.php

@@ -39,4 +39,5 @@ $measurement_type_set = array (
   'number_of_standalone_pages' => 'Number of standalone pages',
   'number_of_written_pages' => 'Number of written pages',
   'number_of_standalone_sheets' => 'Number of standalone sheets',
+  'diameter_image_size' => 'Image size (diameter)',
 );