diff --git a/vocabulary/index.html b/vocabulary/index.html
index f34a3c7..0f23666 100644
--- a/vocabulary/index.html
+++ b/vocabulary/index.html
@@ -167,6 +167,12 @@ <h2>Introduction</h2>
       document are to be interpreted as described in [[!RFC2119]].
     </p>
 
+    <p id="advisement-levels">
+      The key words "strongly encouraged", "strongly discouraged",
+      "encouraged", "discouraged", "can", "cannot", "could", "could not", "might",
+      and "might not" are used for non-normative content.
+    </p>
+
     <section id="termconventions">
 
       <h2>Conventions</h2>