diff --git a/OpenAPI/TS28536_CoslaNrm.yaml b/OpenAPI/TS28536_CoslaNrm.yaml
index 05197c3c7aa4062105db3780ece08c4f8bdaae29..c179fe3b1d4382c8be94512b9eda086b13d5efa6 100755
--- a/OpenAPI/TS28536_CoslaNrm.yaml
+++ b/OpenAPI/TS28536_CoslaNrm.yaml
@@ -169,6 +169,7 @@ components:
                       $ref: '#/components/schemas/ControlLoopLifeCyclePhase'
                     aCCLDisallowedList:
                       type: array
+                      uniqueItems: true
                       items:
                         $ref: '#/components/schemas/ACCLDisallowedAttributes'
                     networkSliceRef: