diff --git a/src/main/cljc/org/domaindrivenarchitecture/activity_pub_poc/activitystreams2.cljc b/src/main/cljc/org/domaindrivenarchitecture/activity_pub_poc/activitystreams2.cljc
index 093e800..4d85c19 100644
--- a/src/main/cljc/org/domaindrivenarchitecture/activity_pub_poc/activitystreams2.cljc
+++ b/src/main/cljc/org/domaindrivenarchitecture/activity_pub_poc/activitystreams2.cljc
@@ -17,14 +17,6 @@
               ::owl/DeprecatedProperty
               ::xsd/anyURI))
 
-;http://www.w3.org/ns/activitystreams#attachment
-(s/def ::attachment 
-  (s/and 
-   ::owl/ObjectProperty
-   ::Class
-   ::Link
-   ::Object))
-
 ;http://www.w3.org/ns/activitystreams#result
 (s/def ::result 
   (s/and 
@@ -33,26 +25,48 @@
    ::Object
    ::Link))
 
+;http://www.w3.org/ns/activitystreams#attachment
+(s/def ::attachment 
+  (s/and 
+   ::owl/ObjectProperty
+   ::Class
+   ::Link
+   ::Object))
+
+;http://www.w3.org/ns/activitystreams#Relationship
+;TODO: definition in progress
+(s/def ::Relationship
+  (s/and (s/keys :opt-un [::object])))
+
 ;http://www.w3.org/ns/activitystreams#Activity
 ;TODO: definition in progress
 (s/def ::Activity 
   (s/and ::Object
-         (s/keys :opt-un [::result])))
+         (s/keys :opt-un [::result
+                          ::object])))
 
-;http://www.w3.org/ns/activitystreams#Object
-;TODO: definition in progress
-(s/def ::Object (s/keys :opt-un [::id ::attachment]))
+;http://www.w3.org/ns/activitystreams#object
+(s/def ::object 
+  (s/and
+   ::owl/ObjectProperty
+   ::Class
+   (s/or ::Object
+         ::Link)))
 
+;http://www.w3.org/ns/activitystreams#object
+(s/def ::Object 
+  (s/keys :opt-un [::id ::Class]))
 
 ;http://www.w3.org/ns/activitystreams#Link
 ;TODO: definition in progress
 (s/def ::Link (s/keys :opt-un [::id]))
 
 ;TODO: There is no as:Class! Why do we need this?
+;Answer jem: I do not want to enhance owl/Class inline from here.
 (s/def
   ::Class
   (s/merge ::owl/Class
-           (s/keys :opt-un [::id])))
+           (s/keys :opt-un [::id ::object])))
 
 
 ;http://www.w3.org/ns/activitystreams#Like
diff --git a/src/test/cljc/org/domaindrivenarchitecture/activity_pub_poc/activitystreams2_test.clj b/src/test/cljc/org/domaindrivenarchitecture/activity_pub_poc/activitystreams2_test.clj
index c9109ac..72a6d86 100644
--- a/src/test/cljc/org/domaindrivenarchitecture/activity_pub_poc/activitystreams2_test.clj
+++ b/src/test/cljc/org/domaindrivenarchitecture/activity_pub_poc/activitystreams2_test.clj
@@ -14,16 +14,27 @@
   (is (not (s/valid? ::sut/id nil)))
   (is (not (s/valid? ::sut/id 2)))
   (is (not (s/valid? ::sut/id "no-uri")))
-  (is (not (s/valid? ::sut/id ["https://social.bla/alyssa/status/RANDOMHASH", "https://social.bla/alyssa/status/RANDOMHASH2"])))
-  )
+  (is (not (s/valid? ::sut/id ["https://social.bla/alyssa/status/RANDOMHASH", "https://social.bla/alyssa/status/RANDOMHASH2"]))))
+
+;TODO: where does the ability for a link reference come from ?
+(deftest object-test
+  (is (s/valid? ::sut/object "http://example.org/posts/1"))
+  (is (s/valid? ::sut/object {:type "Note",
+                              :content "A simple note"}))
+  (is (s/valid? ::sut/object ["http://example.org/posts/1",
+                              {:type "Note",
+                               :summary "A simple note",
+                               :content "That is a tree."}])))
+
+(deftest class-test
+  (is (s/valid? ::sut/Class "https://social.bla/alyssa/status/RANDOMHASH")))
 
 (deftest result-test
   (is (s/valid? ::sut/result "https://social.bla/alyssa/result/RANDOMHASH"))
   (is (s/valid? ::sut/result {:type "http://www.types.example/flightstatus", :name "On Time"}))
   (is (s/valid? ::sut/result {:type "Link" :href "http://www.target.de"}))
   (is (not (s/valid? ::sut/result nil)))
-  (is (not (s/valid? ::sut/result 47)))
-)
+  (is (not (s/valid? ::sut/result 47))))
 
 
 ;(deftest attachment-test