#8 PloneArticle 3.2.1: Alternatives to BaseContentMixin?

I just moved up from PA 2.03, and was wondering if
there is any functionality similar to
BaseContentMixin.py in 3.2? I looked at
AttachmentMixin, but couldn't quite make enough sense
to determine if this was what I was looking for.

Any suggestions or pointing in the right direction
would be greatly appreciated! Thanks!