diff --git a/persistent-outline.el b/persistent-outline.el
index bcee9e6..9e5d052 100644
--- a/persistent-outline.el
+++ b/persistent-outline.el
@@ -20,7 +20,11 @@
 
 ;;; Commentary:
 
-;; Save outline visibility between sessions.
+;; Save outline visibility between sessions.  Currently this module
+;; supports saving to a file-local variable and a dedicated file.  It
+;; is intended to use the dedicated file, but supporting multiple
+;; storage back-ends seemed like a fun hack and not all that hard to
+;; do.
 
 ;;; Code: