Header words 153 through 188 stores up to 18 event times in floating point format.  Each event time is recorded as the number of seconds and fractions of a second that have elapsed since the first sample (designated as 0.0s) of data recorded in the C3D file.

For example, an event time of 1.05 seconds indicates that the event was recorded 1.05 seconds after the first frame of data as recorded in the C3D file header word 4.  It does not matter what frame number is recorded as the first frame – the event occurred 1.05 seconds later.  Thus if the 3D data rate is 50Hz and the first frame number is 51 (one second) then the event occurred after 1.05 seconds of recorded data or 2.05 seconds after frame #1 (which is not recorded in this example).