Which Field is missing from this CAN Datagram?

Color-coded CAN data-frame structure diagram. Top row spans "Bus Idle", "SOF", "Arbitration Field", "Control Field", "Data Field", "CRC Field" ("CRC Sequence", "DEL"), "ACK Field" ("ACK", "DEL"), "EOF", "ITM", and "Bus Idle"; colored blocks and dashed brackets mark their boundaries. Below, a "Standard Format" row contains Identifier, RTR, IDE, r, then a yellow control-field box containing a red question mark. An "Extended Format" row contains Base Identifier, SRR, IDE, Extended Identifier, RTR, r1, r0, and another yellow box with a red question mark. Dashed guide lines connect the lower fields to the upper frame diagram; the question-mark boxes represent unspecified fields.