diff --git a/concise-evidence.cddl b/concise-evidence.cddl
index aa619c6..8d34a64 100644
--- a/concise-evidence.cddl
+++ b/concise-evidence.cddl
@@ -27,4 +27,6 @@ ev-coswid-evidence-map = {
   ? &(ce.coswid-tag-id: 0) => concise-swid-tag-id
     &(ce.coswid-evidence: 1) => evidence-entry
   ? &(ce.authorized-by: 2) => [ + $crypto-key-type-choice ] ; see comid schema
-}
\ No newline at end of file
+}
+
+$domain-type-choice /= environment-map
\ No newline at end of file