Classification Proposal

All,

I was looking over the classification proposal that Jason put together in the STIX Playground document.  I really think this is something that we should do for STIX 2.1. This is super simple and can enable a lot of use cases and interactions with STIX data.
  I would group this in the same class of objects as the "note" and "opinion" objects and as such, I believe we should work on it for STIX 2.1

Bret