diff --git a/docs/api.md b/docs/api.md
index 0e0175db..e8774a30 100644
--- a/docs/api.md
+++ b/docs/api.md
@@ -43,7 +43,6 @@ scheme differs from the original request uri.
 < HTTP/1.1 302 Found
 < Location: https://some-other-site.com/{oid}
 <
-< --git-media.265b3cb3f0530aae9010780a30d92a898400a5582081b21a099d51941eff
 < {binary contents}
 ```
 
@@ -98,13 +97,73 @@ This writes the object contents to the Git Media server.
 * 200 - The object already exists.
 * 201 - The object was uploaded successfully.
 * 307 - The server is returning a different location to send the object.  Clients
-  should retry the PUT against the URL.  The `Authorization` header must _not_ be
+  should retry the PUT against the URL.  See the Redirection section below.
+
+  The `Authorization` header must _not_ be
   passed through if the location's host or scheme differs from the original
   request uri.
 * 409 - The object contents do not match the OID.
 * 403 - The user has **read**, but not **write** access.
 * 404 - The repository does not exist for the user.
 
+#### PUT Redirection
+
+The Git Media API supports offloading storage concerns to a separate storage
+API.  In addition to a 307 response, the Git Media API needs to return one or
+more headers so the client knows how to retry the request.
+
+* `Location` (required) - This is an absolute URL of the new location to send
+the object.
+* `Git-Media-Callback` (optional) - This is an absolute URL of a location to POST
+with the success or failure of the redirected request.
+* `Git-Media-Set-*` (optional) - Instruct the Git Media client for setting other
+headers by setting response headers with this prefix.
+
+##### Example client request
+
+```
+> PUT https://git-media-server.com/objects/{oid}
+> Accept: application/vnd.git-media
+> Content-Type: application/octet-stream
+> Authorization: Basic ...
+> Content-Length: 123
+>
+> {binary contents}
+>
+< HTTP/1.1 307 Temporary Redirect
+< Location: https://simple-storage-service.com/objects/{oid}
+< Git-Media-Callback: https://git-media-server.com/callback
+< Git-Media-Set-Authorization: simple-storage-service-authentication-token
+```
+
+##### Example client redirection
+
+```
+> PUT https://simple-storage-service.com/objects/{oid}
+> Authorization: simple-storage-service-authentication-token
+> Content-Type: application/octet-stream
+> Content-Length: 123
+```
+
+##### Example client callback
+
+The client callback is only made if the 307 redirection returned a
+`Git-Media-Callback` header.  The Git Media client then makes a POST to that
+URL with:
+
+* `oid` - The String OID of the Git Media object.
+* `status` - The HTTP status of the redirected PUT request.
+* `body` - The response body from the redirected PUT request.
+
+```
+> POST https://git-media-server.com/callback
+> Accept: application/vnd.git-media
+> Content-Type: application/vnd.git-media
+> Content-Length: 123
+>
+> {"oid": "{oid}", "status": 200, "body": "ok"}
+```
+
 ## OPTIONS objects/{oid}
 
 This is a pre-flight request to verify credentials before sending the file