diff --git a/doc/syntax.md b/doc/syntax.md
index 1f5d7ee..2c8914c 100644
--- a/doc/syntax.md
+++ b/doc/syntax.md
@@ -33,7 +33,8 @@ error propagation.
 - `nokw`: no keyword. Prevents the rule from matching text that matches a defined kw rule. Essential for
   distinguishing identifiers from keywords (e.g., ensuring var is not parsed as a variable name).
 - `failpass`: pass failure. If this rule fails to parse, the error is reported as a failure of the parent rule,
-  not this specific rule.
+  not this specific rule. Alias definitions are failpass by default.
+- `nofailpass`: discards automatic failpass, e.g. for alias definitions.
 
 ## Expressions