Unify language on truncation between name/displayName, and simplify both

index.bs

@@ -3194,7 +3194,9 @@ associated with or [=scoped=] to, respectively.
 
         When [=clients=], [=client platforms=], or [=authenticators=] display a {{PublicKeyCredentialEntity/name}}'s value, they should always use UI elements to provide a clear boundary around the displayed value, and not allow overflow into other elements [[css-overflow-3]].
 
-        Authenticators MAY truncate characters from the end of a {{PublicKeyCredentialEntity/name}} member's value so that when encoded in UTF-8, its length fits within 64 bytes. See [[#sctn-strings-truncation]] about truncation and other considerations.
+        When storing a {{PublicKeyCredentialEntity/name}} member's value,
+        [=authenticators=] MUST support any value whose length in the UTF-8 character encoding is 64 bytes or less.
+        Authenticators MAY truncate the value as described in [[#sctn-strings-truncation]].
 
 </div>
 
@@ -3266,9 +3268,9 @@ credential.
 
         When [=clients=], [=client platforms=], or [=authenticators=] display a {{PublicKeyCredentialUserEntity/displayName}}'s value, they should always use UI elements to provide a clear boundary around the displayed value, and not allow overflow into other elements [[css-overflow-3]].
 
-        [=Authenticators=] MUST accept and store a {{PublicKeyCredentialUserEntity/displayName}} member's value
-        whose length in the UTF-8 character encoding is 64 bytes or shorter.
-        Authenticators MAY truncate characters from the end of a {{PublicKeyCredentialEntity/displayName}} member's value so that when encoded in UTF-8, its length fits within 64 bytes. See [[#sctn-strings-truncation]] about truncation and other considerations.
+        When storing a {{PublicKeyCredentialUserEntity/displayName}} member's value,
+        [=authenticators=] MUST support any value whose length in the UTF-8 character encoding is 64 bytes or less.
+        Authenticators MAY truncate the value as described in [[#sctn-strings-truncation]].
 </div>