What are Durations?

The sum of durations for any (equipment) unit will equal the total duration of the shift.

Durations are calculated to the nearest 0.1 of an hour. Therefore, when they are summed there can be a total error of 0.05 hours multiplied by the number of records for each unit.

There can be a further error since very short durations (< 0.05 hours) are rounded up to 0.1 hours to ensure short stoppages are reported.

The event times for every change of equipment status, including shift stoppages, are stored. These take no account of shift start and end times.

A later process removes all occurrences where an equipment unit has two consecutive records with the same status. This allows for the calculation of the absolute elapsed time of statuses, particularly maintenance.