The CAT NMS Plan requires the trade event to be reported with the “time of execution”. Each exchange has different rules governing open outcry trading on the exchange floors. Thus, the eventTimestamp should be the execution time as recognized per the rules of the exchange on which the trade was executed.

The eventTimestamp must be reported with a minimum precision of seconds.  If the eventTimestamp is captured in more precise granularity, it must be reported to that level of precision (up to nanoseconds).  Please see FAQ B2 for more information about timestamp granularity.