diff --git a/APIs/schemas/transporttype-response-schema.json b/APIs/schemas/transporttype-response-schema.json
index 394a3ae..df4be8a 100644
--- a/APIs/schemas/transporttype-response-schema.json
+++ b/APIs/schemas/transporttype-response-schema.json
@@ -13,9 +13,15 @@
       ]
     },
     {
-      "description": "Any transport type URN base defined in the Transports register of the NMOS Parameter Registers",
+      "description": "Any transport type URN base defined by an AMWA specification in the Transports register of the NMOS Parameter Registers",
       "type": "string",
       "pattern": "^urn:x-nmos:transport:[a-zA-Z0-9_]+$"
+    },
+    {
+      "description": "Any manufacturer-specific transport type URN base defined in the Transports register of the NMOS Parameter Registers",
+      "not": {
+        "pattern": "^urn:x-nmos:"
+      }
     }
   ],
   "format": "uri"