Promotions: Reject Cart Promotion If Cart Contains Products From A Category

How to stop/reject a cart promotion when entering a coupon code if the cart contains products in a specified category?

In other words, promotions in cart can only be cart or catalog, but not both.

I think you would have to add the category to a section of the promotion regarding "the following are NOT true". It should be possible within the standard system. One of the folks here who more actively use promotions should be able to give you the specifics.

Thank you! That did it.