diff --git a/srv/TSTExecutorExpand.srv b/srv/TSTExecutorExpand.srv
index 072ae9211dfd5fea0fe1a2d49d25da08810621b8..d156d6752378ba5681cfa0cefe519dda04a0350f 100644
--- a/srv/TSTExecutorExpand.srv
+++ b/srv/TSTExecutorExpand.srv
@@ -5,6 +5,7 @@
 string ns       # Namespace for the tstfactory
 int32 id        # id for the TST node in the tstfactory
 int32 free_id	# First free unique id
+string[] possible_units		# List of posssible units. Needed to declare constraints vars.
 ---
 int32 free_id	# Returns the first free unique id in the delegation
 bool success