Whilst I agree with Otto (and others), how about making it really simple by avoiding technical terms?
Ross ---- Index: ifstated.conf.5 =================================================================== RCS file: /cvs/src/usr.sbin/ifstated/ifstated.conf.5,v retrieving revision 1.13 diff -u -p -r1.13 ifstated.conf.5 --- ifstated.conf.5 18 Jun 2018 06:04:25 -0000 1.13 +++ ifstated.conf.5 7 Dec 2018 02:59:43 -0000 @@ -90,7 +90,8 @@ interfaces this equals the init state. .Pp In contrast to link state tests, external tests must be run periodically to evaluate their status. -The frequency at which an external test is run has to be set with the +The interval in seconds between (starts of) runs of an external test is set +with the .Ar every keyword. .Pp