diff --git a/os2.rkt b/os2.rkt
index 700e67a..8309c59 100644
--- a/os2.rkt
+++ b/os2.rkt
@@ -84,6 +84,7 @@
 ;; role in a conversation.
 (struct topic (role pattern virtual?) #:prefab)
 
+;; BootK = PID -> Transition
 ;; InterruptK = State -> Transition
 ;; TrapK<X> = X -> InterruptK