You can define the rating services to be used when a PICS filtering rule is applied.
Typically, PICS labels are not obtained from individual Web sites themselves (although the PICS specifications do not forbid Web sites from including their own PICS rating labels), but from a separate entity called a rating service. A rating service is a company or other organization that evaluates Web content according to its own, published criteria. The rating service is identified by a URL that it includes in all of the labels that the service assigns. Because the service identifier is a URL, it can be used to retrieve a document that gives a description of the rating service and its rating system.
A label bureau is the part of the rating service that distributes the PICS labels. The label bureau also has an identifying URL, which the PICS filtering client software uses to request the labels from the rating service.
Caching Proxy administrators can elect to trust one or more of these service providers and can configure the proxy server to accept only ratings supplied by the organizations that they trust.
Use the PICS Filter Service Information configuration page to add, modify, or remove service information definitions. A service definition specifies the ratings bureau that generates the labels used in PICS filtering. You can specify more than one service definition; services are consulted in the order in which they are listed. If you have more then one active service information definition, the requested URL must pass all filters according to all rating services in order for the URL to be served to the requesting client.
The proxy server compares values and categories specified in the filter rules to values given by the label bureau to determine if the URL's content is acceptable or unacceptable.