HTML and CSS Reference
browser's status box
We argue that the contents of the tag itself should explain the link, but
sometimes window space is tight and an expanded explanation is help-
ful, such as when the link is in a table of contents.
18.104.22.168. The rel and rev attributes
The optional rel and rev attributes for the <a> tag express a formal re-
lationship and direction between source and target documents. The rel
attribute specifies the relationship from the source document to the tar-
get, and the rev attribute specifies the relationship from the target to
the source. Both attributes can be placed in a single <a> tag, and the
browser may use them to specially alter the appearance of the anchor
content or to automatically construct document navigation menus. Oth-
er tools also may use these attributes to build special link collections,
tables of contents, and indexes.