diff --git a/51.md b/51.md
index b3256f79..1fd3ef58 100644
--- a/51.md
+++ b/51.md
@@ -21,8 +21,9 @@ stored in the `.content`.
 
 ## Standard lists
 
-Users are expected to have a single list of each of these types. They have special meaning and clients may
-rely on them to augment the user profile or browsing experience.
+Standard lists use non-parameterized replaceable events, meaning users may only have a single list
+of each kind. They have special meaning and clients may rely on them to augment a user's profile or
+browsing experience.
 
 For example, _mute lists_ can contain the public keys of spammers and bad actors users don't want to see in
 their feeds or receive annoying notifications from.