Abstract: A data representation and protocol are provided to interface two networks. A plurality of information units to be transmitted from one network to another are formatted into a variable size block in accordance with the protocol. Each block contains a header field storing a total information unit count and a control information unit count. The remainder of the block stores the actual information itself, both control and data, in consecutive byte locations, with the actual control information located at the end of the block. The block can then be sent to another network for processing. A device in the other network need only reference the block header to determine whether the information contained in the block is control or data. This speeds the processing of large quantities of either all data information and/or control information.