Rule Type Change

[fast-turtle-9]

I have been using the change type rule and wanted to know if a certain behavior is possible.
I am working with data in which a field can go from F to C and C to F. monitoring the change in the status. Is it possible to only alert when it goes from C to F and not when it goes from F to C or is it only possible to alert on both?
Tried looking for something in the documentation, but could not find anything.
Thank you.

[jertel]

You can use an enhancement to check the value and raise a DropMatchException if you don't want an alert to trigger.