clean up the use of milestone

@@ -1571,12 +1571,6 @@ NOTE 2  A Plan for Activity can define a number of part activities which are rel
 """^^xsd:string ;
   rdfs:label "Plan for activity"^^xsd:string ;
   rdfs:subClassOf :ClassOfActivity ;
-  rdfs:subClassOf [
-      rdf:type owl:Restriction ;
-      owl:minQualifiedCardinality "0"^^xsd:nonNegativeInteger ;
-      owl:onClass :Milestone ;
-      owl:onProperty :hasActivity ;
-    ] ;
 .
 :PlanForILAP
   rdf:type owl:Class ;