diff --git a/gtfs/spec/en/reference.md b/gtfs/spec/en/reference.md
index 7f8ff23aa..8217a2d83 100644
--- a/gtfs/spec/en/reference.md
+++ b/gtfs/spec/en/reference.md
@@ -436,7 +436,7 @@ Describes levels in a station. Useful in conjunction with `pathways.txt`, and is
 
 File: **Optional**
 
-Primary key (`*`)
+Primary key (`table_name`, `field_name`, `language`, `record_id`, `record_sub_id`, `field_value`)
 
 In regions that have multiple official languages, transit agencies/operators typically have language-specific names and web pages. In order to best serve riders in those regions, it is useful for the dataset to include these language-dependent values.