From the article: "it’s a really good idea to go and read the UEFI specification. You can do this. It’s very easy. You don’t have to pay anyone any money. [...] You can find it [right here on the official UEFI site]. You have to check a couple of boxes, but you are not signing your soul away to Satan, or anything."

Before people click on that link and start thinking the author of the article is a damn liar (the link takes one to a menacing "Access Denied" page which prompts users to login or register (which in turn involves filling out a form and possibly paying a large amount of money)), here is a link to free downloads of the specification documents (as PDF files):

http://www.uefi.org/specifications

And by the way, no need to check any boxes at all, just click any of the links and the download should start right away.