Either this isn't possible or I am searching the web/forum using wrong search
terms.

I have created a very robust 'timesheet' form which allows users to select a
radio button "bi-weekly" or "bi-monthly". This clears the "work period
ending" date field using a macro. (the "work period ending" field is used to
fill the rest of the dates (previous 14 days for bi-weekly, 13-16 days for
bi-monthly) I have other 'bells and whistles' to ensure it is error/dummy
proof so it can be deployed and used by any level of user. But the one issue
I can't get around is how to clear the value of a different cell without
using a macro. I don't want macros because, if a user doesn't enable macros,
I don't want the unexpected behavior.

I am basically trying to:

In cell A1
clear the contents in cell C1 if a change in vallue B1 from "Bi-Monthly" to
"Bi-Weekly" or from "Bi-Weekly" to "Bi-Monthly" occurs. If no change, don't
reset the form.

I have wracked my brain on this for many hours.... I have never tried to
effect the content of an external cell based on formula of the current cell
(without VB, a macro or a formula in the 'external' cell itself.... I don't
even know if Excel allows it.

Thanks in advance for expert advice. Reading the other forum responses
seeking an answer I have learned quite a bit... most importantly, that if
anyone can help it is you guys!

Casey