diff --git a/docs/reference/formats/html.json b/docs/reference/formats/html.json
index d6c7672966..7c2f253173 100644
--- a/docs/reference/formats/html.json
+++ b/docs/reference/formats/html.json
@@ -35,6 +35,10 @@
         "name": "abstract-title",
         "description": "Title used to label document abstract"
       },
+      {
+        "name": "categories",
+        "description": "List of categories used to classify the document."
+      },
       {
         "name": "doi",
         "description": "Displays the document Digital Object Identifier in the header."
@@ -784,4 +788,4 @@
       }
     ]
   }
-]
\ No newline at end of file
+]