diff --git a/CppCoreGuidelines.md b/CppCoreGuidelines.md
index 7332146..3be01b8 100644
--- a/CppCoreGuidelines.md
+++ b/CppCoreGuidelines.md
@@ -19754,7 +19754,17 @@ Additions to `std` might clash with future versions of the standard.
 
 ##### Example
 
-    ???
+    namespace std { // BAD: violates standard
+        class My_vector {
+        //     . . .
+        };
+    }
+
+    namespace Foo { // GOOD: user namespace is allowed 
+        class My_vector {
+        //     . . .
+        };
+    }
 
 ##### Enforcement
 
diff --git a/scripts/hunspell/isocpp.dic b/scripts/hunspell/isocpp.dic
index 1b582cb..2e6796f 100644
--- a/scripts/hunspell/isocpp.dic
+++ b/scripts/hunspell/isocpp.dic
@@ -347,6 +347,7 @@ Murray93
 mutex
 mutexes
 mx
+My_vector
 MyCustomError
 MyException
 myMap