diff --git a/index.html b/index.html
index 3075bc3f..40da8ed3 100644
--- a/index.html
+++ b/index.html
@@ -343,7 +343,8 @@ editor.replace('bar');</code></pre>
     bindKey: {win: 'Ctrl-M',  mac: 'Command-M'},
     exec: function(editor) {
         //...
-    }
+    },
+    readOnly: true // false if this command should not apply in readOnly mode
 });</code></pre>
                         </div>