diff --git a/README.md b/README.md
index 107ae3c..dbae2bd 100644
--- a/README.md
+++ b/README.md
@@ -38,6 +38,7 @@ Using comments, we'll include the following attributes
 * content_checksum: A sha256 hash of the file contents, excluding the front matter.
 
 ## Optional Metadata
+* file_name: name of the file, otherwise guessed from the url
 * parent_revision: in the case of Gist style services, 
 * signature: A Base 64 Signature
 * public_key: The public key component for signature verification