Add TODO to describe more keywords.
diff --git a/doc/puffs-the-language.md b/doc/puffs-the-language.md
index 083e155..447955e 100644
--- a/doc/puffs-the-language.md
+++ b/doc/puffs-the-language.md
@@ -12,7 +12,7 @@
 
 ## Keywords
 
-The Puffs language has 24 keywords. 7 of those introduce top-level concepts:
+7 keywords introduce top-level concepts:
 
 - `const`
 - `error`
@@ -57,6 +57,8 @@
 
 - `limit`
 
+TODO: categorize and, or, not, as, false, true, in, out, this, u8, u16, etc.
+
 
 ## Operators