I had a quick look at the full list of Schema.org tags, which are now available in Google CSEs. They can be used to filter the CSE’s site list, serving to “Restrict pages from the above site list to only those that contain [chosen] Schema.org types”. Handy if you have a huge single site of HTML/CSS/XML that you can grep, and you want to prepare it for selective CSE search without having to juggle directories and file names.

It looks to me like those tagging open access scholarly articles would need to be able to chain Schema.org tags into something like…

CreativeWork: ScholarlyArticle: TransferAction: DownloadAction: GiveAction:

Whereas paywall publishers might need something like:

CreativeWork: ScholarlyArticle: TransferAction: DownloadAction: SellAction:

But at present there seems to be only the basic undifferentiated…

CreativeWork: ScholarlyArticle:

Even if there were workable OA additions to Schema.org, there would still the huge problems of: i) persuading people to add the tags to all their ongoing content at the article level, and to do so correctly and consistently; and ii) to have them go back and accurately tag perhaps two decades or more of existing open access articles.