diff --git a/force_bdss/core/data_value.py b/force_bdss/core/data_value.py
index c1240531bf37065964e7fc1af5c47cf4dbd667b2..9da19abdd53a7ecd59b3a808a93bb2d5fdef1bb7 100644
--- a/force_bdss/core/data_value.py
+++ b/force_bdss/core/data_value.py
@@ -1,4 +1,4 @@
-from traits.api import HasStrictTraits, Any, String, Enum
+from traits.api import HasStrictTraits, Any, String, Enum, Bool
 
 
 class DataValue(HasStrictTraits):
@@ -22,6 +22,9 @@ class DataValue(HasStrictTraits):
     #: A flag for the quality of the data.
     quality = Enum("AVERAGE", "POOR", "GOOD")
 
+    # Set by the engine. True if the data value contains a KPI.
+    is_kpi = Bool(False)
+
     def __str__(self):
 
         s = "{} {} = {}".format(
@@ -31,4 +34,8 @@ class DataValue(HasStrictTraits):
             s += " +/- {}".format(str(self.accuracy))
 
         s += " ({})".format(str(self.quality))
+
+        if self.is_kpi:
+            s += " (KPI)"
+
         return s