diff --git a/doc/formatting.md b/doc/formatting.md
index 9d9b62f..abeb5e4 100644
--- a/doc/formatting.md
+++ b/doc/formatting.md
@@ -19,4 +19,5 @@ It's quite simple on client-side, but server-side has to supply more info:
 > ↗️ COMMAND: content
 > ↙️ :server 421 nick COMMAND: :Unknown command
 > ```
-> For more info on colon prefixes, see [Colon Prefixing](prefixing.md)
\ No newline at end of file
+> For more info on colon prefixes, see [Colon Prefixing](prefixing.md)  
+> For more info on error 421, see [Unknown Command](notfound.md)
\ No newline at end of file