diff --git a/doc/formats/index.md b/doc/formats/index.md
index 540e273..8bba8ec 100644
--- a/doc/formats/index.md
+++ b/doc/formats/index.md
@@ -72,8 +72,8 @@ remake.
     * `*.MAP`
     * `*.TXT`
 * `Menu/`
-    * `*.mnu` # plain text, linked to .obj file, contains definitions
-    * `*.obj` # unknown, not 3D .obj format
+    * [`*.mnu`](mnu.md) # plain text, linked to .obj file, contains definitions
+    * [`*.obj`](obj.md)
 * `Misc/`
     * `occlusio.lis` # plain text, presumably occlusion mappings?
 * [`MultiMaps/`](maps.md#multimaps)
diff --git a/doc/formats/mnu.md b/doc/formats/mnu.md
new file mode 100644
index 0000000..7d96e59
--- /dev/null
+++ b/doc/formats/mnu.md
@@ -0,0 +1,6 @@
+# *.mnu
+
+These files appear to be the UI definitions for Chaos Gate. Some relate to
+system menus, other to in-game menus.
+
+