The Federal Trade Commission proposed additional changes to the Children's Online Privacy Protection Act Rule. The revised rule would clarify that operators of websites who choose to use advertising services and plug-ins that collect data about children would have to comply with COPPA. The rule would also allow mixed-audience websites to age-screen visitors, and would clarify the circumstances in which persistent identifiers such as cookies or IP addresses are considered "personal information." The revisions modify an earlier rule that was proposed by the FTC in September 2011. EPIC commented on the September 2011 rule, noting that "the proposed revisions update the COPPA Rule by taking better account of the increased use of mobile devices by users and of new data collection practices by businesses." For more information, see EPIC: Children's Online Privacy Protection Act and EPIC: Federal Trade Commission.