diff --git a/src/digimarks/models.py b/src/digimarks/models.py
index bada175..34e403c 100644
--- a/src/digimarks/models.py
+++ b/src/digimarks/models.py
@@ -1,3 +1,8 @@
+"""Models for digimarks.
+
+Contains the bookmarks administration, users, tags, public tags and more.
+"""
+
 from datetime import UTC, datetime
 from http import HTTPStatus
 from typing import Optional, Type, TypeVar
@@ -25,6 +30,7 @@ class Visibility:
 
     VISIBLE = 0
     DELETED = 1
+    HIDDEN = 2
 
 
 # Type var used for building custom types for the DB