epicproc will filter the events lists (filterevents is set to true by default) with the selectlib expression given in filterexpression. The filtering is destructive by default, that is to say the filtered events are physically removed from the event lists. This behavior can be changed by setting the parameter flagfilteredevents to true. In this case all events will be retained, and a flag column will be set to indicate what events would have been removed. Refer to evselect for details on the destructive and non-destructive filtering.
The default filtering expressions for epicproc make use of the XMM events attribute flags (see evatt), and should be suitable for most users.