diff --git a/52.md b/52.md
index 133e3b36..03382873 100644
--- a/52.md
+++ b/52.md
@@ -65,6 +65,8 @@ Example:
     ["d", "<random-identifier>"],
 
     ["title", "<title of calendar event>"],
+    ["summary", "<brief description of the calendar event>"],
+    ["image", "<string with image URI>"],
 
     // dates
     ["start", "<YYYY-MM-DD>"],
@@ -93,8 +95,6 @@ Aside from the common tags, this also takes the following tags:
 
 * `start` (required) inclusive start Unix timestamp in seconds. Must be less than `end`, if it exists.
 * `end` (optional) exclusive end Unix timestamp in seconds. If omitted, the calendar event ends instantaneously.
-* `start_tzid` (optional) time zone of the start timestamp, as defined by the IANA Time Zone Database. e.g., `America/Costa_Rica`
-* `end_tzid` (optional) time zone of the end timestamp, as defined by the IANA Time Zone Database. e.g., `America/Costa_Rica`. If omitted and `start_tzid` is provided, the time zone of the end timestamp is the same as the start timestamp.
 
 ```yaml
 {
@@ -114,9 +114,6 @@ Aside from the common tags, this also takes the following tags:
     ["start", "<unix timestamp in seconds>"],
     ["end", "<unix timestamp in seconds>"],
 
-    ["start_tzid", "<IANA Time Zone Database identifier>"],
-    ["end_tzid", "<IANA Time Zone Database identifier>"],
-
     // location
     ["location", "<location>"],
     ["g", "<geohash>"],