diff --git a/docs/fs.md b/docs/fs.md
index 03031d0..a30b641 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -15,3 +15,15 @@
     - **fopen.json:** contains all of the informations about the FOD disc (title, icon filename, starting point etc.)
 - **MENU:** contains menu files in FOpen Interactive Markup format, more informations on the documentation page
 - **VIDEO:** contains video titles in MKV format, these must follow the standard specs
+
+## Metadata File (fopen.json)
+```json
+{
+  "title": "EFN",
+  "icon": "icon.png",
+  "start": "MENU 1"
+}
+```
+- **title:** title of the FOD project, may be optionally shown on players
+- **icon:** the filename of 256x256 PNG file in the "META" folder that will be used as icon, may be optionally shown on players
+- **start:** the starting point of the FOD, it's characterized by the type of start point ("MENU" or "VIDEO") and it's ID
\ No newline at end of file