The roles in a Smart Links infrastructure are:
The author creates content and posts it on the Internet.
The author's role is to define a title, a description and tags for the posted content. Smart Links then use this information to classify and retrieve the content.
The authority is either the home of the content or a service provider for the author.
Deciding how smart links will look like in text is simple enough. After all they are based on HTTP queries. The project just needs to define a query format, its semantics and possibly different levels of implementation. If you already put a search box on a web site that is all quite straightforward.
On the other hand the smart links infrastructure promises some tougher challenges.
Traditional hyperlinks are based on web addresses like the ones you type in the address bar of your browser. If you make typo, the web page will not load. If its address changed, the page will not load.
The purpose of smart links is to help you find a web page even if you don't know precisely where it is. In particular, the adoption of smart links will greatly reduce broken links.
Smart links also enable new ways of linking content together, without relying on rigid web addresses or on a single search engine. They free the Internet from its old memes.