>Unfortunately it's proprietary code that I'm not at liberty to share.

I was hoping it wasn't, but certainly respect that.

>The lowest level classes are fairly abstract, but they do have some code in methods that most all subclasses have a need to use.
>
>I think one of the biggest factors in developing your BO classes is to start with a general outline of what you want and then begin developing your tree. Say you decide to put functionality XYZ at some level of the tree and you get it working. Then you find while working on a different BO branch that it is needing the same functionality. So you need to be able to either promote the XYZ method up to a higher level class they both inherit from, or potentially insert a new parent class that these two classes would be derived from.
>
>Don't be afraid to refactor a few times until you get it right. Don't be afraid to scrap parts that just don't work as well as they should.

Yes I understand that method, but am still looking for something more specific to BO. If you find a good published reference that you think may help I'd appreciate it. Thanks.