How To Get Features Listed In Google Sitemap?

The reference guide states that it's possible to include 'extended feature pages' in the sitemap.

The sitemap options have a setting for brand/Manufacturer feature pages. This is set to yes.

Currently only brands show up in the sitemap. I want Google to index other important feature pages.

How can I add other features to the sitemap?

Is there a way to define what features should go in the sitemap and what features should not?

Only extended features.

Could you please explain what an 'extended feature' is?

When creating a new feature, in the options list you would need to select Brand/Manufacturer in the Type list. I believe they used to call it Extended.

Edit: What other kinds of features do you want in the feed?

Just like brands there are other features that can be significant. Basically anything that is a major concept in the niche the site is in. Mostly concepts that could almost be a category. Things that people will search for in Google. Features are essentially content tags.

Only extended feature variants has own pages and URLs as well. What kind of URL do you want to show for example for the simple text feature?