diff --git a/rfc/0012_authentication_file_format_v1.md b/rfc/0012_duniterkey_authentication_file_format_v1.md
similarity index 88%
rename from rfc/0012_authentication_file_format_v1.md
rename to rfc/0012_duniterkey_authentication_file_format_v1.md
index 1cb6309a62d42bce6c4c3e2df38043d991e96336..2144fee86e4a4b3ffcd6096705d11d97e97cf6cf 100644
--- a/rfc/0012_authentication_file_format_v1.md
+++ b/rfc/0012_duniterkey_authentication_file_format_v1.md
@@ -9,13 +9,19 @@ Last edited: 2020-02-12
 License: GPL-3
 ```
 
-# Authentication File Format
+# Duniterkey Authentication File Format
 
-This document serves as a reference for a interoperable authentication file format.
+This document serves as a reference for the `.duniterkey` authentication file format.
+
+## Limitations
+
+This format is a container format. Its main caveat is that you can have inside a data not be compatible with your application.
+
+This is the same problem as video containers. The video codec inside the container can be unreadable by your application.
 
 ## File format extension
 
-Cesium client use the ".duniterkey" extension. So for now, the official extension is `.duniterkey`.
+The official extension is `.duniterkey`.
 
 ## Text File Format