// User data length: (variable length field, LE)
header.writeVariableShort(length);
// Total length: (LE)
header.writeShortLE(length);
// PDU type: Confirm Active PDU (0x3), TS_PROTOCOL_VERSION (0x10) (LE)
header.writeShortLE(0x13);
// PDU source: 1004 (LE)