3.1.4.2 MSG_GETBLKLIST Initiation
To initiate a Retrieval Protocol query for the list of block ranges on a server, the higher-layer applications MUST specify a server address, a segment ID, and a set of block ranges within the segment identified by the segment ID. The client instance of the Retrieval Protocol instantiation MUST construct and send a GetBlockList message (MSG_GETBLKLIST (section 2.2.4.2)) to the server, store it in the Outstanding Request List (3.1.1), and start the Request Timer (3.1.2). The SegmentID and NeededBlocksRange fields of the GetBlockList message correspond to the segment ID and the set of block ranges supplied by the higher-layer applications.