Rules & Modules: Implementing DataTypes

The rules documentation is pretty good all around; but, in my instance I have a custom module which stores data in a non-identifiable table.
In order to provide a user-supplied identifier, it looks as if Rules only allows me to utilize ONE field.

What can I do to implement a data type comprised of:
( nid (node:nid), vid (node:vid), uid (user:uid), model (string), serial (string), registered (date), purchdate (date) ).

NID/UID/MODEL/SERIAL should be adequate to identify the specific product registered to a user.
If its absolutely necessary, I could even get away without NID.

Or have I misunderstood how data types are used in Rules?

(my module, (not yet approved) uc_product_registration will need Rules integration, so the file I've attached is a work-in-progress).

Thanks for your help!