Help with recurring events, RUNT expressions

Hello,

First I wanted to thank everyone on this list for all their input, it
helps newbs like me tremendously.

I was hoping that someone could help me. I just don’t understand how
to come up with runt temporal expressions.

I am trying to generate a rule/expression that accounts for the
following infomation.

Rule 1: recurring event every n days with a specific start and end date

Rule 2: recurring event every n days with a specific start date and no
end date.

Thanks for any help, again I just can’t comprehend how to do this.