Howdy -- unfortunately, you cannot have a CMR relationship with a BMP bean... a CMR relationship means demands that *both* sides of the relationship are managed by the Container, so there's just no way you can do it. Although as Phillipe said, a CMR field is the component interface of an entity bean, and there's nothing in that interface that explicitly makes it a CMP vs. BMP bean, Bean Law (i.e. the spec rules) insists that one bean can have a relationship only with other CMP beans.
Unless the Container is "in charge" of both sides of the relationship (and it doesn't really matter if it is uni- or bi-directional), it would not be able to maintain referential integrity, or handle things like cascading deletes.
So, just remember that CMR = Container-Managed Relationship and Container-Managed Relationship means you MUST use Container-Managed Persistence on BOTH sides of the relationship. Both partners must use CMP.
The Container is a control freak
Now, that doesn't mean that you can't mix and match CMP and BMP beans in an app--only that they can't be in an official CMR relationship with one another.
cheers,
Kathy