diff --git a/src/relaxng/plots.rnc b/src/relaxng/plots.rnc
index 3c29ba4e0b..a7c657864d 100644
--- a/src/relaxng/plots.rnc
+++ b/src/relaxng/plots.rnc
@@ -26,6 +26,14 @@ element plots {
         attribute components { list { xsd:int+ } }) &
       (element background { list { xsd:int+ } } | 
         attribute background { list { xsd:int+ } })
+    }* &
+    element meshlines {
+      (element meshtype { ( "tally" | "entropy" | "ufs" | "cmfd" ) } |
+        attribute meshtype { ( "tally" | "entropy" | "ufs" | "cmfd" ) }) &
+      (element id { xsd:int } | attribute id { xsd:int })? &
+      (element linewidth { xsd:int } | attribute linewidth { xsd:int }) &
+      (element color { list { xsd:int+ } } | 
+        attribute color { list { xsd:int+ } })?
     }*
   }*
 }