diff --git a/Volume-Server-API.md b/Volume-Server-API.md
index ee9ae05..1468432 100644
--- a/Volume-Server-API.md
+++ b/Volume-Server-API.md
@@ -46,6 +46,7 @@ The size returned is the size stored on SeaweedFS, sometimes the file is automat
 | Content-Type | use the specified content type | "application/octet-stream" |
 | Content-MD5  | verify the uploaded content by MD5 | empty |
 | Authorization | Json Web Token for writes issued by master | empty |
+| Seaweed-xxxxx | Any key-value pair with `Seaweed-` prefix | empty |