Google has completely revamped the documentation for article structured data in their developer section. It is really a complete rewrite, specifically to call out the differences between article markup for AMP pages versus article markup for normal HTML pages.

Aaron Bradly did the hard work and summarized on Google+ the changes, so I’ll just quote it here if you hate Google+:

Property use now described separately for AMP and non-AMP pages

Previously a property was either required or recommended, irrespective of page type. Now each property’s usage requirements are governed by whether it’s an AMP page or not. For example, the image property is required by AMP, but only recommended for non-AMP pages. There are now, in fact, no required properties for non-AMP pages.

There’s now a new category of usage for properties, “ignored”. This is universally a property annotation that appears for non-AMP pages, and applies to most properties that are used by AMP: of the 17 properties enumerated only five are recommended, with the remainder being ignored.

It seems that if you want richer results and you use structured data, the way to go is with AMP.

Here are screen shots of the before and after of the top of the doc pages:

Before:

Now:

Make sure you review the new docs over here.

Forum discussion at Google+.