diff --git a/os2.rkt b/os2.rkt
index 7c7e379..e19f54a 100644
--- a/os2.rkt
+++ b/os2.rkt
@@ -88,7 +88,7 @@
 ;; role in a conversation.
 (struct topic (role pattern virtual?) #:prefab)
 
-;; BootK = PID -> Transition
+;; BootK = either (PID -> Transition) or Transition
 ;; InterruptK = State -> Transition
 ;; TrapK<X> = X -> InterruptK