[wp-hackers] post format types

[Mike Schinkel]

On Jan 6, 2011, at 4:46 PM, Otto wrote:
> All a "format" really is is a string. If there's enough need for a
> standardized format (by which I mean something a lot of themes will
> probably use) then there's no reason it can't be added eventually. For
> example, I was thinking "event" would be a pretty good one to have in
> core.

I proposed Event on Trac and it was pointed out to me that Events really make more sense as custom post types vs. post formats, and I realized they were most likely correct.  

So what's the rule of thumb when considered CPT vs. PF? (ignoring the option "custom" aspect of the former?  Maybe it's that Post Formats don't presume to use additional data elements that would disappear if displayed using the default format such as "Date" and "Venue?" Or is that too restrictive?

-Mike