11.4.4 ACT Interrupts
When Active Clock Tuning is enabled (ACTEN = 1) and
                                    either the ACTLOCK or ACTORS bits change state (e.g.,
                                    from a Locked to an Unlocked state), the ACT Interrupt Flag
                                    (ACTIF) of the PIR registers is set (ACTIF =
                                    1). If the ACT Interrupt Enable (ACTIE) bit is
                                    set (ACTIE = 1), an interrupt will be generated
                                    when ACTIF becomes set. No interrupts are generated for each
                                                OSCTUNE update unless the
                                    update results in a change of Lock status or Out-of-Range
                                    status.
