diff --git a/20.md b/20.md
index e76942ab..9a96f6df 100644
--- a/20.md
+++ b/20.md
@@ -68,6 +68,19 @@ Event rejected, insufficient proof-of-work difficulty
     ["OK", "b1a649ebe8...", false, "pow: difficulty 26 is less than 30"]
 
 
+
+Client Handling
+---------------
+
+`messages` are meant for humans, with `reason:` prefixes so that clients can be slightly more intelligent with what to do with them. For example, with a `rate-limited:` reason the client may not show anything and simply try again with a longer timeout.
+
+For the `pow:` prefix it may query relay metadata to get the updated difficulty requirement and try again in the background.
+
+For the `invalid:` and `blocked`: prefix the client may wish to show these as styled error popups.
+
+The prefixes include a colon so that the message can be cleanly separated from the prefix by taking everything after `:` and trimming it.
+
+
 Future Extensions
 -----------------