The HTML5 spec states:
Each link created for a link element
is handled separately. For instance,
if there are two link elements with
rel="stylesheet", they each count as a
separate external resource, and each
is affected by its own attributes
independently. Similarly, if a single
link element has arelattribute with
the valuenext stylesheet, it creates
both a hyperlink (for the next
keyword) and an external resource link
(for the stylesheet keyword), and they
are affected by other attributes (such
as media or title) differently.
http://dev.w3.org/html5/spec/Overview.html#attr-link-rel
What would be a use case for using rel="next stylesheet" in the same <link> tag?
I believe that example was made up simply to illustrate the point that one can use both an external resource and a hyperlink keyword in the same
linktag. From the list of link types,stylesheetseems to be the only external resource type in common use, which is why I guess it was chosen for this example. Thenextcould have very well beenprevor any other hyperlink keyword.