A label consists of a service identifier, label options, and a rating. The service identifier is the URL chosen by the rating service (see PICS Ratings Services and Ratings Systems) as its unique identifier. Label options give additional properties of the document being rated as well as the rating itself, such as the time the document was rated. The rating itself is a set of attribute-value pairs that describe a document along several dimensions. One or more labels may be distributed together as a list. The general form for a label list (formatted for presentation, and not showing error status codes) is: ------------------
Following the usual HTTP distinction between HEAD and GET, a client that wishes to examine a rating before retrieving the full document can substitute the word HEAD for GET in the request. The server responds with exactly the headers shown above, but does not send back the document foo.html.