src/HOL/IsaMakefile

 $(LOG)/HOL-UNITY.gz: $(OUT)/HOL UNITY/ROOT.ML\
   UNITY/Channel.ML UNITY/Channel.thy UNITY/Common.ML UNITY/Common.thy\
   UNITY/Client.ML UNITY/Client.thy  UNITY/Comp.ML UNITY/Comp.thy\
   UNITY/Deadlock.ML UNITY/Deadlock.thy UNITY/FP.ML UNITY/FP.thy\
   UNITY/Union.ML UNITY/Union.thy UNITY/Handshake.ML UNITY/Handshake.thy\
+  UNITY/Extend.ML UNITY/Extend.thy\
   UNITY/LessThan.ML UNITY/LessThan.thy UNITY/Mutex.ML UNITY/Mutex.thy\
   UNITY/Network.ML UNITY/Network.thy UNITY/Reach.ML UNITY/Reach.thy\
   UNITY/SubstAx.ML UNITY/SubstAx.thy UNITY/Token.ML UNITY/Token.thy\
   UNITY/Traces.ML UNITY/Traces.thy UNITY/UNITY.ML UNITY/UNITY.thy\
   UNITY/WFair.ML UNITY/WFair.thy UNITY/Lift.ML UNITY/Lift.thy\