diff --git a/marketplace/scribblings/concepts.scrbl b/marketplace/scribblings/concepts.scrbl
index 38f52c7..8969df7 100644
--- a/marketplace/scribblings/concepts.scrbl
+++ b/marketplace/scribblings/concepts.scrbl
@@ -81,6 +81,10 @@ structures.
 actions the process wishes to perform. See @secref{Actions} for the
 possible actions a process can take.
 
+Note that the result of an event handler function is actually a
+@racket[Transition] structure; the actual Typed Racket type of event
+handlers is @racket[TrapK], defined in @secref{handler-functions}.
+
 @section{What is a VM?}
 
 @deftech[#:key "vm"]{Virtual Machines (VMs)} are simply a collection
@@ -135,6 +139,8 @@ Roles have three parts:
 
 ]
 
+@section[#:tag "messages-and-topics"]{Messages and Topics}
+
 @deftech{Messages} are simply Racket data structures. They can be any
 value for which @racket[equal?] is defined, any @racket[#:prefab]
 structure, most @racket[#:transparent] structures, or any non-object
diff --git a/marketplace/scribblings/highlevel.scrbl b/marketplace/scribblings/highlevel.scrbl
index 16a11b3..342eb0e 100644
--- a/marketplace/scribblings/highlevel.scrbl
+++ b/marketplace/scribblings/highlevel.scrbl
@@ -96,15 +96,6 @@ its state type).
 
 }
 
-@section{Constructing topics and roles}
-
-As previously mentioned, @tech{topics} are ordinary Racket values
-which may have embedded wildcards. The identifier @racket[?] produces
-a fresh wildcard value for use in topic patterns.
-
-For example,
-TODO
-
 @section{Constructing transitions}
 **** transition, transition:, transition/no-state
 **** cons-trees of actions; null, false, void; use of (when)
@@ -113,6 +104,7 @@ TODO
 @section{Actions}
 **** Communication-related
 ***** endpoint, endpoint:
+[#:tag "endpoint-dsl"]
 ***** delete-endpoint
 ***** send-message
 ***** send-feedback
diff --git a/marketplace/scribblings/lowlevel.scrbl b/marketplace/scribblings/lowlevel.scrbl
index 7e20b0e..1dd1f3c 100644
--- a/marketplace/scribblings/lowlevel.scrbl
+++ b/marketplace/scribblings/lowlevel.scrbl
@@ -18,7 +18,7 @@ the @emph{system call interface} of a Unix-like operating system. The
 @secref{high-level-interface} corresponds to the @emph{C library
 interface} of a Unix-like operating system.
 
-@section{Handler Functions}
+@section[#:tag "handler-functions"]{Handler Functions}
 
 Each @deftech{handler function} is always associated with a particular
 @tech{endpoint}, registered with the VM via