Sites are an extension to the XFN policies.
Sites can be named relative to
The enterprise root
An organizational unit
Sites named relative to the enterprise root are the same as sites named relative to the top organizational unit. Given an organization name, you can compose a name for its site context by using one of the namespace identifiers, site or _site. For example, if the enterprise root is ../doc.com the context for naming sites relative to the enterprise root is ../doc.com/site. Sites would have names like ../doc.com/site/alameda.
The following objects can be named relative to a site name:
Services at the site, such as the site schedule or calendar, printers, and faxes
The file service available at the site
These objects are named by composing the site name with the namespace identifier of the target object's namespace and the name of the target object. For example, the name site/Clark.bldg-5/service/calendar names the calendar service of the conference room Clark.bldg-5 and is obtained by composing the site name site/Clark.bldg-5 with the service name service/calendar. (See "Composing Names Relative to Sites" for a more detailed description of naming objects relative to sites.)