Before revision: The number of bytes of data contained in this record is "Byte Count Field" minus 4 ( that is, 3 bytes for "24-bit Address Field" and 1 byte for "Checksum Field").
After revision: The number of bytes of data contained in this record is "Byte Count Field" minus 4 ( that is, 3 bytes for "24-bit Address Field" plus 1 byte for "Checksum Field").