diff --git a/OpenAPI/TS28561_NdtNrm.yaml b/OpenAPI/TS28561_NdtNrm.yaml
index 31d58a42f8787142558a5d3ed940b1a283312509..99a8eea625a7eb8ae656ce09484fd6e71ceb9f9f 100644
--- a/OpenAPI/TS28561_NdtNrm.yaml
+++ b/OpenAPI/TS28561_NdtNrm.yaml
@@ -31,6 +31,7 @@ components:
           supportedNDTCapabilities:
             type: array
             uniqueItems: true
+            minItems: 1
             items:
               $ref: '#/components/schemas/NDTCapability'
             description: >-
@@ -77,6 +78,7 @@ components:
           nDTJobOutputData:
             type: array
             uniqueItems: true
+            minItems: 1
             items:
               $ref: '#/components/schemas/NDTOutputDataPoint'
             description: It indicates the list of NDTOutput(s) that are provided by the NDT function as the output for any task executed in an instantiated NDT job.
@@ -199,10 +201,13 @@ components:
       properties:
         performanceDataName:
           type: string
+          maxItems: 1
         performanceDataValue:
           type: integer
+          maxItems: 1
         performanceDataScalingFactor:
           type: integer
+          maxItems: 1
 
   #------Definition of JSON arrays for name-contained IOCs ---------------#