diff --git a/23.md b/23.md
index 42912281..7a06b0ef 100644
--- a/23.md
+++ b/23.md
@@ -12,7 +12,11 @@ This NIP defines `kind:30023` (a parameterized replaceable event according to [N
 
 ### Format
 
-The `.content` of these events should be a string text in Markdown syntax.
+The `.content` of these events should be a string text in Markdown syntax. To maximize compatibility and readability between different clients and devices, any client that is creating long form notes:
+
+- MUST NOT hard line-break paragraphs of text, such as arbitrary line breaks at 80 column boundaries.
+
+- MUST NOT support adding HTML to Markdown.
 
 ### Metadata