diff --git a/15.md b/15.md
index 8c2d5feb..98cc8a34 100644
--- a/15.md
+++ b/15.md
@@ -88,7 +88,7 @@ Fields that are not self-explanatory:
 {
   // "stall_id": <string, id of the stall to which this product belong to>,
   "name": <string, product name>,
-  "type": <simple | variable | variation>,
+  "type": <string, "simple" | "variable" | "variation">,
   "description": <string (optional), product description>,
   "images": <[string], array of image URLs, optional>,
   "currency": <string, currency used>,