diff --git a/dataspace-patterns.prs b/dataspace-patterns.prs
new file mode 100644
index 0000000..2740763
--- /dev/null
+++ b/dataspace-patterns.prs
@@ -0,0 +1,11 @@
+version 1 .
+
+; Dataspace patterns: a sublanguage of attenuation patterns.
+Pattern = DDiscard / DBind / DLit / DCompound .
+
+DDiscard = <_>.
+DBind = <bind @name symbol @pattern Pattern>.
+DLit = <lit @value any>.
+DCompound = @rec  <compound <rec @label any @arity int> @members { int: Pattern ...:... }>
+          / @arr  <compound <arr @arity int>            @members { int: Pattern ...:... }>
+          / @dict <compound <dict>                      @members { any: Pattern ...:... }> .
diff --git a/dataspace.prs b/dataspace.prs
index eadbd9a..3160df1 100644
--- a/dataspace.prs
+++ b/dataspace.prs
@@ -1,9 +1,4 @@
 version 1 .
 embeddedType Actor.Ref .
 
-;As implemented
-Observe = <Observe @label symbol @observer embedded>.
-
-; ;As will be implemented soon
-; Observe = <Observe @pattern Pattern @observer embedded>.
-.
+Observe = <Observe @pattern dataspace-patterns.Pattern @observer #!any>.
diff --git a/gatekeeper.prs b/gatekeeper.prs
index 7673518..d8be377 100644
--- a/gatekeeper.prs
+++ b/gatekeeper.prs
@@ -1,5 +1,5 @@
 version 1 .
 embeddedType Actor.Ref .
 
-Resolve = <resolve @sturdyref sturdy.SturdyRef @observer embedded>.
-Bind = <bind @oid any @key bytes @target embedded>.
+Resolve = <resolve @sturdyref sturdy.SturdyRef @observer #!#!any>.
+Bind = <bind @oid any @key bytes @target #!any>.
diff --git a/protocol.prs b/protocol.prs
index 1fe9c20..b86a66d 100644
--- a/protocol.prs
+++ b/protocol.prs
@@ -11,4 +11,4 @@ TurnEvent = [@oid Oid @event Event].
 Assert = <assert @assertion Assertion @handle Handle>.
 Retract = <retract @handle Handle>.
 Message = <message @body Assertion>.
-Sync = <sync @peer embedded>.
+Sync = <sync @peer #!#t>.
diff --git a/secure-chat-protocol.prs b/secure-chat-protocol.prs
index 951e950..c20c8e0 100644
--- a/secure-chat-protocol.prs
+++ b/secure-chat-protocol.prs
@@ -3,9 +3,16 @@ embeddedType Actor.Ref .
 
 UserId = int .
 
-Join = <joinedUser @uid UserId @handle embedded>.
+Join = <joinedUser @uid UserId @handle #!Session>.
 
-NickClaim = <claimNick @uid UserId @name string @k embedded>.
+Session = @observeUsers <Observe =user @observer #!UserInfo>
+        / @observeSpeech <Observe =says @observer #!Says>
+        / NickClaim
+        / Says
+.
+
+NickClaim = <claimNick @uid UserId @name string @k #!NickClaimResponse>.
+NickClaimResponse = #t / NickConflict .
 
 UserInfo = <user @uid UserId @name string>.