diff --git a/resources/schema/CORE-base.json b/resources/schema/CORE-base.json
index 1619ba6da..d6a660437 100644
--- a/resources/schema/CORE-base.json
+++ b/resources/schema/CORE-base.json
@@ -84,7 +84,7 @@
           "type": "string"
         },
         {
-          "pattern": "^([A-Z]{2}|[A-Z]{4}|SUPP[A-Z]{2}|SUPP[A-Z]{4}|SQAP[A-Z]{4})$",
+          "pattern": "^((?!AP)[A-Z]{2}|[A-Z]{4}|SUPP[A-Z]{2}|SUPP[A-Z]{4}|SQAP[A-Z]{4})$",
           "type": "string"
         }
       ]