Is it possible to use "not" logical operator in a Business Rule Condition?

This seems like a very simple request to me, but I cannot see any other questions/answers about it.

Can I add a "not" to my Conditions in a Business Rule?

My scenario is that I have a core Entity with a Type.  The Type is a domain attribute with a Code and Name.  The Code of the core Entity should in the form 'AA-9999', where 'AA' is the Code from Type.

The idea is that I have a business rule with the condition "not Code starts with DBA.Type.Code" and the Action would be "Code is not valid".

Is this possible?  Is there a better way of implementing this?

Thanks,

Michael