diff --git a/documentation/CARD_KEYS b/documentation/CARD_KEYS
index 61e271d..e92a650 100644
--- a/documentation/CARD_KEYS
+++ b/documentation/CARD_KEYS
@@ -48,6 +48,9 @@ Card keys with special meanings known so far:
   Notes:
     - Rolodex keys are usually email addresses (as restricted by the welcome
       UI), but anything is probably fine.
+    - If we want to share rolodex data between events, we should consider using
+      a key of hmac(shared_secret,email_address) to preserve the privacy of
+      attendees.
 
 "event_key"
   This is not really part of a visitor's persisted card, but is sent with it for
diff --git a/example_print_badge_input b/example_print_badge_input
index e7b0527..5a28b63 100644
--- a/example_print_badge_input
+++ b/example_print_badge_input
@@ -3,7 +3,7 @@
 	"last_name": "Brannigan",
 	"tags": "Leela, Velour, Karaoke",
 	"shdh_number": "12",
-	"key": "zbrannigan@nimbus.doop"
+	"key": "zbrannigan@nimbus.doop",
   "badge_icons": null,
   "attended_shdh_12": 1229171859,
   "event_key": "shdh_12"