Document Menu/*.mni files

doc/formats/index.md

@@ -70,8 +70,9 @@ remake.
 * [`Maps/`](maps.md)
     * `*.MAP`
     * `*.TXT`
-* `Menu/`
-    * [`*.mnu`](mnu.md) # plain text, linked to .obj file, contains definitions
+* [`Menu/`](mnu.md) - UI element definitions
+    * `*.mni`
+    * `*.mnu`
     * [`*.obj`](obj.md)
 * `Misc/`
     * `occlusio.lis` # plain text, presumably occlusion mappings?

doc/formats/mnu.md

@@ -122,3 +122,14 @@ Submenus also show a couple of unique values:
 | `SUBMENUID`   | `1`, `2`, `3` | As `MENUID`   |
 | `SUBMENUTYPE` | `0`, `1`, `2` | As `MENUTYPE` |
 
+It seems .mnu files can also include other files, which have the extension
+`.mni` (presumably for "Menu include"). Examples:
+
+```
+*
+$GenDialog.mni
+$GenLoad.mni
+```
+
+It looks like we just interpolate the named file into the text when we come
+across one of these lines.