22.214.171.124 HTTP Header Fields Introduced by the BITS Upload Protocol
BITS-Packet-Type (section 126.96.36.199): The value MUST be Ack for this message.
BITS-Received-Content-Range: This refers to the start offset of the next fragment message that the client MUST send. For example, if the fragment contained the range 128–212, this value MUST be set to 213. This field MUST be included.
BITS-Session-Id (section 188.8.131.52).
BITS-Reply-URL: This header MUST NOT be present when the Ack pertains to a simple upload. For an upload with reply, this header MUST be present if the fragment triggering the Ack is the last fragment of a request entity (that is, if the range of the fragment includes the final byte of the request entity). The header SHOULD NOT be present in Acks to other fragments.
BITS-Error (section 184.108.40.206): This field MUST be present if the server encountered an error processing the request and MUST NOT be present otherwise.
BITS-Error-Context (section 220.127.116.11): This field MUST be present if the server encountered an error processing the request and MUST NOT be present otherwise.