In addition to the absolute event time stamp, the ASDU 2 type requires that the message also contains a fault number and relative time data. However, these are not available in the IEC 61850 data model. Therefore, the IEC 60870-5-103 stack automatically creates a fault number, which is incremented each time the IED's internal IEC 61850 data attribute LD0.LEDPTRC1.Str.general (Start LED) is activated. Relative time is calculated from the time stamp of this same IEC 61850 data attribute. Relative time is represented as a 16 bit millisecond value which saturates to its maximum value 65535 ms if necessary.