XHTML Friends Network
XHTML Friends Network ( XFN ) is a metadata profile to display personal connections through links on the World Wide Web and in social networks. The profile makes the rel attribute of a link exploited to allow humans and machines to describe differentiated personal human contact and be seen. XFN was developed by Tantek Çelik, WordPress developer Matthew Mullenweg and Eric Meyer. It is a technique that can be assigned to the Social Software and the Semantic Web.
Use
XFN is a simple way to categorize their personal contacts in the blogroll or link collections for authors of blogs. You can specify, for example, via a XFN value if you have a contact really knows and has already met once in person (met), if a contact is a work colleague ( co -worker ) or whether a contact is a friend ( friend ). Single or multiple values can be assigned to the rel attribute of the element in HTML.
Example
Here you can see how the rel attributes of hyperlinks one or more values are assigned. Multiple values can be add by spaces. These values can be read by various programs again. These types of programs called spiders or crawlers.
Jane Dave Darryl James Expert specification
Terms:
Friendship
Only one possible value;
Physically
Profession
Geographically
Only one possible value;
Family
Only one possible value;