Apply suggestions from code review 3

Co-authored-by: =JeffH <jdhodges@google.com>

index.bs

@@ -1391,9 +1391,10 @@ that are returned to the caller when a new credential is created, or a new asser
         will be an {{AuthenticatorAssertionResponse}}.
 
     :   <dfn>authenticatorAttachment</dfn>
-    ::  The value SHOULD be a member of {{AuthenticatorAttachment}} used to communicate to the [=authenticator=], and Relying Parties SHOULD treat unknown values as if the value were null.
-        This attribute may be used by RPs in conjunction with {{isUserVerifyingPlatformAuthenticatorAvailable}} to prompt the user to register a platform authenticator if it is available and the user is currently being authenticated 
-        with a cross-platform attachment. See [[#sctn-authenticator-attachment-modality]].
+    ::  This attribute reports the [=authenticator attachment modality=] in effect at the time this {{PublicKeyCredential}} was created.
+        The attribute’s value SHOULD be a member of {{AuthenticatorAttachment}}. [=[RPS]=] SHOULD treat unknown values as if the value were null.
+
+        Note: If, as the result of a [=registration ceremony|registration=] or [=authentication ceremony=], {{AuthenticatorAttachment}}'s value is "cross-platform" and concurrently {{isUserVerifyingPlatformAuthenticatorAvailable}} returns [TRUE], then the user employed a [=roaming authenticator=] for this [=ceremony=] while there is an available [=platform authenticator=]. Thus the [=[RP]=] has the opportunity to prompt the user to register the available [=platform authenticator=], which may enable more streamlined user experience flows.
 
     :   {{PublicKeyCredential/getClientExtensionResults()}}
     ::  This operation returns the value of {{PublicKeyCredential/[[clientExtensionsResults]]}}, which is a [=map=] containing
@@ -1864,10 +1865,7 @@ a numbered step. If outdented, it (today) is rendered either as a bullet in the
                     ::  |id|
 
                     :   {{PublicKeyCredential/authenticatorAttachment}}
-                    ::  The value of the authenticator attachment type used to communicate to the [=authenticator=]. 
-                        Values SHOULD be members of the {{AuthenticatorAttachment}} enum based on the transport used 
-                        by authenticator during registration. If the user agent does not
-                        have any authenticator attachment information, set the value to null.
+                    ::  A {{DOMString}} whose value SHOULD be a member of {{AuthenticatorAttachment}}, based on the [[#enum-transport|transport]] used by the [=authenticator=] during the [=registration ceremony=], as determined per [[#sctn-attachments-from-transports]].
 
                     :   {{PublicKeyCredential/response}}
                     ::  A new {{AuthenticatorAttestationResponse}} object associated with |global| whose fields are:
@@ -2239,10 +2237,7 @@ When this method is invoked, the user agent MUST execute the following algorithm
                         <code>|assertionCreationData|.[=credentialIdResult=]</code>.
 
                     :   {{PublicKeyCredential/authenticatorAttachment}}
-                    ::  The value of the authenticator attachment type used to communicate to the [=authenticator=]. 
-                        Values SHOULD be members of the {{AuthenticatorAttachment}} enum based on the transport used 
-                        by authenticator during authentication. If the user agent does not
-                        have any authenticator attachment information, set the value to null.
+                    ::  A {{DOMString}} whose value SHOULD be a member of {{AuthenticatorAttachment}}, based on the [[#enum-transport|transport]] used by the [=authenticator=] during the [=authentication ceremony=], as determined per [[#sctn-attachments-from-transports]].
 
                     :   {{PublicKeyCredential/response}}
                     ::  A new {{AuthenticatorAssertionResponse}} object associated with |global| whose fields are: