Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Boost Website Design FAQ

Why are links "underlined"? The website follows some simple design principles to make the site as widely accessible as practical. The style for links within document text are underlined to have a non-color, clear, visual indicator that it is a link. Underlines provide the most familiar indicator to people because of the historical default usage by web browsers.

Why are not "standard" underlines used for links? The use of the bottom border provides for considerable more flexibility in style than the underline font style. It is important to have such freedom to be able to indicate the various states links can be in. In the case of the Boost design the bottom border underline is used to represent the difference between internal vs. external links, and between visited and unvisited links. All of which are orthogonal to the text being a link.

Why are not all links underlined? When it is clear from the context that the text is a link the underline is ommited to reduce visual clutter, as this is also within a context under which the text is already a collection of links. For such situations the design uses a link box context. All such links are placed within a light grey bordered box to indicate that the items within it are links.