diff --git a/OpenAPI/genericNrm.yaml b/OpenAPI/genericNrm.yaml
index b48192857f172290c2d355eaeba8d3752aa1ec34..d49758e3b3a8456960ec4cdcf49f6947619dc521 100644
--- a/OpenAPI/genericNrm.yaml
+++ b/OpenAPI/genericNrm.yaml
@@ -1180,15 +1180,29 @@ components:
       properties:
         id:
           type: string
+          nullable: true
+        objectClass:
+          type: string
+        objectInstance:
+          $ref: 'comDefs.yaml#/components/schemas/Dn'
         VsDataContainer:
           $ref: '#/components/schemas/VsDataContainer-Multiple'
+      required:
+        - id
     Top:
       type: object
       properties:
         id:
           type: string
+          nullable: true
+        objectClass:
+          type: string
+        objectInstance:
+          $ref: 'comDefs.yaml#/components/schemas/Dn'
         VsDataContainer:
           $ref: '#/components/schemas/VsDataContainer-Multiple'
+      required:
+        - id
 
 #-------- Definition of IOCs with new name-containments defined in other TS ------