In reply to Sarah Gooding.

A Post Format is a theme feature ... a piece of meta information...

Yes, and a Piston is a feature of a heat-engine that converts thermal energy to linear thrust. But from that "information", it would be impossible to identify a piston laying among objects on a workbench ... much less create one or know how to 'enhance' an engine with it.

Before long, I will be able to Seahawks the Post Formats Quiz.

But spot one in a Police lineup of data-objects? Beautify & enrich a website with one (beyond clicking a radio button)? Um ... let me get back to you on that. ;)
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In all candor, folks, I think I'm pointing to the actual "problem" that Post Formats is experiencing. They are presented & discussed in an abstracted fashion, leaving people to watch each other for cues as they alternately nod & shake their heads.

They aren't being adopted & used by end-users, because treatments of the topic lack ... accessibility.