HTML4 definition of the 'class' attribute. This meta data profile defines some 'class' attribute values (class names) and their meanings as suggested by a draft of "Hypertext Links in HTML":

xoxo

A XOXO outline as defined by the XOXO specification. Typically an ordered list <ol> or unordered list <ul> element.

blogroll

When used with the aforementioned 'xoxo' value, this value means a particular instance of a XOXO outline which has the additional semantic of being a blogroll.