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603 lines
27 KiB
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
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"http://www.w3.org/TR/html401/loose.dtd">
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<html lang="en">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta http-equiv="PICS-Labels"
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content='(PICS-1.1 "http://www.rsac.org/ratingsv01.html" l by "martinm@raleigh.ibm.com" on "1996.06.24T10:11-0500" exp "1998.06.06T08:00-0500" r (n 0 s 0 v 0 l 0))'>
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<meta http-equiv="PICS-Label"
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content='(PICS-1.1 "http://www.classify.org/safesurf/" l by "martinm@raleigh.ibm.com" on "1996.06.24T15:38-0500" exp "1998.06.06T08:00-0500" r (SS~~000 1))'>
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<title>Platform for Internet Content Selection (PICS)Platform for Internet
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Content Selection (PICS)</title>
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<!-- Embedded PICS rating using RSACi. This page has no sex, violence, bad language, nor nudity. -->
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<meta http-equiv="PICS-Labels"
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content='(PICS-1.1 "http://www.rsac.org/ratingsv01.html" l by "martinm@raleigh.ibm.com" on "1996.06.24T10:11-0500" exp "1997.06.06T08:00-0500" r (n 0 s 0 v 0 l 0))'>
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<!-- Embedded PICS rating using SafeSurf. This page is acceptable for all ages. -->
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<meta http-equiv="PICS-Label"
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content='(PICS-1.1 "http://www.classify.org/safesurf/" l by "martinm@raleigh.ibm.com" on "1996.06.24T15:38-0500" exp "1997.06.06T08:00-0500" r (SS~~000 1))'>
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<!-- Changed by: Paul Resnick, 24-Dec-1997 -->
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<link rev="made" href="mailto:pics-ask@w3.org">
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<!-- Embedded PICS rating using RSACi. This page has no sex, violence, bad language, nor nudity. -->
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<!-- Embedded PICS rating using SafeSurf. This page is acceptable for all ages. -->
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<style type="text/css">
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BODY { color: black; background: white }
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.header-example { margin-left: 2em }</style>
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</head>
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<body>
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<p><a href="../"><img src="../Icons/WWW/w3c_home" alt="W3C"
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border="0"></a></p>
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<h1><img alt="PICS" src="../Icons/WWW/pics_69x112_8g" align="top">
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Platform for Internet Content Selection (PICS)</h1>
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<div style="border: solid thick red; padding: 1em"><p>This document is not currently maintained as PICS
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has been superseded by the Protocol for Web Description Resources (<a href="/2007/powder/">POWDER</a>). W3C encourages authors and
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implementors to refer to POWDER (or its successor) rather than PICS when developing systems to describe Web content or agents to
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act on those descriptions. A brief document outlining the advantages offered by POWDER compared with PICS is <a href="/2009/08/pics_superseded.html">available
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separately</a>. The <a href="http://www.w3.org/standards/techs/pics" title="PICS Current Status Page">Current Status Page</a> lists
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the PICS Recommendations and in each case includes a link to the document that supersedes it.</p>
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<p>Contact details of the individuals named below and links to other documents may no longer be active.</p>
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</div>
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<p>The <b>PICS</b><a
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href="http://www.w3.org/Consortium/Legal/ipr-notice.html#W3C Trademarks"><font
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color="#FF0000"><sup><sup>TM</sup></sup></font></a> specification enables
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labels (metadata) to be associated with Internet content. It was originally
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designed to help parents and teachers control what children access on the
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Internet, but it also facilitates other uses for labels, including code
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signing and privacy. The PICS platform is one on which other rating services
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and filtering software have been built.</p>
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<h2>Table of Contents</h2>
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<ul>
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<li><a href="#Introduction">Introduction</a></li>
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<li><a href="#Participating">Participating</a></li>
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<li><a href="#New">What's New</a></li>
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<li><a href="#Media">Media information</a></li>
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<li><a href="#links">What Governments, Media, and Individuals are Saying
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about PICS (pro and con)</a></li>
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<li><a href="#Specs">Technical Specifications</a></li>
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<li><a href="#Developers">Resources for developers of software and labeling
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services</a></li>
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<li><a href="#Products">Lists of PICS-compatible products and
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services</a></li>
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<li><a href="defaults.html">Hints on self-labeling</a></li>
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<li><a href="#Innovations">Innovative uses of PICS labels</a></li>
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<li><a href="#RDF">RDF</a></li>
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</ul>
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<h2>See also</h2>
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<ul>
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<li><a href="http://www.w3.org/2000/03/PICS-FAQ">PICS Frequently Asked
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Questions</a></li>
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</ul>
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<h2>_________</h2>
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<p> </p>
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<h2><a name="Introduction">Introduction</a></h2>
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<p>For introductory materials, we suggest:</p>
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<ul>
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<li><a href="principles.html">PICS Statement of Principles</a> and <a
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href="http://www.w3.org/TR/NOTE-PICS-Statement">Statement on Using PICS
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Well</a>.</li>
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<li><a href="http://www.research.att.com/~lorrie/pubs/tech4kids/">Technology
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Inventory</a>. Lorrie Cranor and Paul Resnick.</li>
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<li><a href="http://www.sciam.com/0397issue/0397resnick.html">Filtering
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Information on the Internet</a> [broken link as of July 2005].
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Paul Resnick. <i>Scientific American</i>,
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March 1997, pp. 106-108.</li>
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<li><a href="iacwcv2.htm">PICS: Internet Access Controls Without
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Censorship</a>, Paul Resnick and Jim Miller, <i>Communications of the
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ACM</i>, 1996, vol. 39(10), pp. 87-93.</li>
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<li><a href="PICS-FAQ-980126.html">PICS and Intellectual Freedom FAQ.</a>
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Paul Resnick.</li>
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</ul>
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<h2><a name="Participating">Participating</a></h2>
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<p>W3C maintains two electronic mailing lists for public use:</p>
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<ul>
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<li><a name="pics-info"></a><b>PICS-info@w3.org</b> is where we distribute
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public announcements related to the PICS project. Anyone may subscribe by
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sending email to <b>PICS-info-request@w3.org</b> with the word "Subscribe"
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in the Subject: field.</li>
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<li><b>PICS-ask@w3.org</b> is for the public to send questions about the
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PICS project.</li>
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</ul>
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<p>PICS also maintains special purpose <a href="#Developers">mailing lists for
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developers</a>. There is also a <a href="IG/">PICS Interest Group</a> for W3C
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members and invited participants.</p>
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<div style="border: solid thick red; padding: 1em"><p>The PICS Interest Group and mailing lists have now been closed but
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archives remain available:</p><ul>
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<li><a href="http://lists.w3.org/Archives/Public/pics-info/">PICS Info</a></li>
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<li><a href="http://lists.w3.org/Archives/Public/pics-interest/">PICS Interest</a></li>
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</ul></div>
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<h2>What's <a name="New">New</a></h2>
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<ul>
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<li><a href="http://www.w3.org/TR/rdf-pics">PICS Rating Vocabularies in
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XML/RDF</a> (W3C NOTE 27 March 2000)</li>
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<li><a href="http://www.w3.org/TR/NOTE-PICS-Statement">Statement on Using
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PICS Well</a> (1 June 1998)</li>
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<li><a href="http://www.w3.org/TR/REC-DSig-label/">PICS Signed Labels (DSig)
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1.0 Specification</a> (27 May 1998)</li>
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<li><a href="refcode/Overview.html">PICS Reference Code</a> (2/98)</li>
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<li><a href="http://www.w3.org/TR/REC-PICSRules">PICSRules Language for
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Writing Filtering Rules</a>; a W3C <a
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href="http://www.w3.org/Consortium/Process">Recommendation</a>
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(12/97)</li>
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<li><a
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href="http://www.w3.org/Policy/Documents/TBLGILC_Response.html">Letter
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from Tim Berners-Lee to GILC</a> about PICSRules. Tim Berners-Lee
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(12/97)</li>
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<li><a href="PICS-FAQ-980126.html">PICS and Intellectual Freedom FAQ.</a>
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Paul Resnick. Updated filtering section to include brief discussion of
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PICSRules. (updated 1/97)</li>
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<li><a
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href="http://www.w3.org/People/Reagle/stuff/PICSRules_Response.html">PICSRules
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and Free Speech.</a> Joseph Reagle. General comments and Joseph's
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responses to posts on the fight-censorship mailing list. (12/97)</li>
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<li>Free <a href="refcode/Parser/">Java implementation</a> of parsers for
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PICS labels, services, and rules, evaluator for PICSRules (12/97)</li>
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<li><a href="http://www.w3.org/TR/PR-DSig-label">DSIG 1.0 specification for
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signing PICS labels</a>; a W3C <a
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href="http://www.w3.org/Consortium/Process">Proposed Recommendation</a>
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(12/97)</li>
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<li><a href="http://www.surfwatch.com">SurfWatch</a> available in PICS
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format. <a href="http://www.si.umich.edu/~presnick/PICS-incubator/">The
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PICS Application Incubator</a> [broken link as of March 2005] at The University of Michigan School of
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Information created a PICS label bureau to distribute SurfWatch
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labels. (12/97)</li>
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<li><a href="http://www.ics.raleigh.ibm.com/WebTrafficExpress">IBM's
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PICS-compliant proxy server</a> released (12/97)</li>
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<li><a href="http://www.netshepherd.com">Net Shepherd and Alta Vista offer
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filtered Internet search</a> (11/97)
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[broken link as of July 2005]</li>
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</ul>
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<h2>Information for the <a name="Media">Media</a></h2>
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<p>For inquiries about PICS, please refer to
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<a href="../Consortium/contact.html#press">W3C's press contact
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information</a>.</p>
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<p>Please direct technical inquiries to:</p>
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<ul>
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<li><a href="mailto:pics-ask@w3.org">W3C PICS expert</a>,
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(pics-ask@w3.org)</li>
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<li><a href="mailto://swick@w3.org">Ralph R. Swick</a>, (<a
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href="mailto:swick@w3.org">swick@w3.org</a>), W3C metadata lead. +
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1.617.253.2613</li>
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</ul>
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<p>Inquiries about public policy issues surrounding content regulation may
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also be directed to</p>
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<ul>
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<li><a href="mailto://reagle@w3.org">Joseph Reagle</a> (<a
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href="mailto://reagle@w3.org">reagle@w3.org</a>), W3C Policy Analyst. +
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1.617.253.2613</li>
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<li><a href="mailto:djweitzner@w3.org">Danny Weitzner</a>, (<a
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href="mailto:djweitzner@w3.org">djweitzner@w3.org</a>), W3C Technology and
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Society Domain Leader. + 1.617.253.2613</li>
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</ul>
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<h2><a name="links"></a>What others are saying about PICS</h2>
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<h3>Governments</h3>
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<ul>
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<li><a
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href="http://www.europarl.eu.int/dg1/a4/en/a4-97/a4-0098.htm">European
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Commission Report (follow-on document of 20 March, 1997)</a></li>
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<li><a href="http://www.aba.gov.au/what/online/index.htm">Australian
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Broadcast Authority report on its investigation into on-line
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services</a></li>
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<li><a
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href="http://europa.eu.int/en/record/green/gp9610/protec.htm">European
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Parliament Green Paper: the Protection of Minors and Human Dignity in
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Audiovisual and Information Services</a></li>
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<li><a href="http://europa.eu.int/en/record/legal/index.htm">European Union
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Communication on illegal and harmful content on the Internet</a>
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[broken link as of July 2005]</li>
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<li><a href="http://www2.echo.lu/legal/en/internet/content/wpen.html">Report
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of European Commission Working party on illegal and harmful content on the
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internet</a> [broken link as of July 2005]</li>
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<li><a href="http://www2.echo.lu/best_use/best_use.html">European Commission
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Forum for Exchange of Information on Internet Best Practices</a>
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[broken link as of July 2005]</li>
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</ul>
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<h3>Media</h3>
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<ul>
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<li><a href="http://www.wired.com/news/news/technology/story/9176.html">PICS
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Walks Fine Line on Net Filtering</a></li>
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<li><a
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href="http://www.hotwired.com/packet/garfinkel/97/05/index2a.html">Good
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Clean PICS: The most effective censorship technology the Net has ever seen
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may already be installed on your desktop</a>(Simson Garfinkel in HotWired:
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February 1997)</li>
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<li><a href="http://www.collegehill.com/ilp-news/reagle.html">College Hill
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interview with Joseph Reagle, W3C staff member</a>
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[broken link as of July 2005]</li>
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</ul>
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<h3>Individuals and Organizations</h3>
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<ul>
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<li><a href="http://www.eff.org/policies/filtration_policy.html">EFF's Draft
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Policy on public interest principles for online filtration, ratings, and
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labeling systems</a> [broken link as of July 2005].
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Suggested guidelines for responsible use of labeling
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and filtering.</li>
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<li><a href="http://www.bluehighways.com/tifap/">The Internet Filter
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Assessment Project.</a> A group of librarians with mixed feelings about
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filtering examined several products in detail and discussed the issues
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facing libraries.</li>
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<li><a href="http://www.aclu.org/issues/cyber/burning.html">ACLU White Paper
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Critical of Labeling and Filtering</a>
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[broken link as of July 2005]</li>
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<li><a href="http://www.irdu.nus.sg/~wayne/paper.html">PICS-Aware Proxy
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System vs. Proxy Server Filters.</a>
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[broken link as of July 2005] Wayne Salamonsen and Roland Yeo,
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proceedings of INET '97.</li>
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<li><a href="http://www.ariadne.ac.uk/issue9/pics/">Metadata, PICS and
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Quality.</a> Chris Armstrong. Ariadne magazine, May 1997.</li>
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<li><a href="http://www.msen.com/~weinberg/rating.htm">Rating the Net</a>.
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Jonathan Weinberg. in Hasting Communications and Entertainment Law
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Journal, Vol. 19, No. 2, p. 453-482. (A balanced but critical academic's
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look at rating systems and their legal and social impact.)</li>
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<li><a href="http://www.pobox.com/~rene/liberty/label.html">The Net Labeling
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Delusion</a> (anti-PICS web site in Australia)</li>
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<li><a href="http://www.eff.org/~declan/fight-censorship/">Fight-censorship
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mailing lists</a> [broken link as of July 2005]
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(Declan McCullagh's moderated and unmoderated lists;
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occasional discussion of PICS and related technologies).</li>
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</ul>
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<h2>__________</h2>
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<h2><a name="Specs">PICS Technical Specifications</a></h2>
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<h3>Completed Specifications for PICS-1.1</h3>
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<p>These are official W3C recommendations. They are stable. The normative
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specifications are in English. <a href="translations">Translations</a> of
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some of these are available.</p>
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<ol>
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<li><a href="http://www.w3.org/TR/REC-PICS-services"><strong><em>Service
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descriptions</em></strong>:</a> Specifies the format for describing a
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rating service's vocabulary and scales; analogous to a database
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schema.</li>
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<li><em><a href="http://www.w3.org/TR/REC-PICS-labels"><strong>Label format
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and distribution</strong>:</a></em> Specifies the format of labels and
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methods for distributing both self-labels and third-party labels.</li>
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<li><strong><em><a
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href="http://www.w3.org/TR/REC-PICSRules">PICSRules:</a></em></strong>
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Specifies an interchange format for filtering preferences, so that
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preferences can be easily installed or sent to search engines.</li>
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</ol>
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<ol start="4">
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<li><b><i><a href="http://www.w3.org/TR/REC-DSig-label/">PICS Signed Labels
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(DSig) 1.0 Specification</a></i></b><a
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href="http://www.w3.org/TR/PR-DSig-label">:</a> Specifies the syntax and
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semantics of digital signatures in PICS labels.</li>
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</ol>
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<h3>Special Supplements to the Specifications</h3>
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<p>These are not official W3C recommendations, but they do represent a
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consensus of the PICS working group.</p>
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<ol start="5">
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<li><a href="defaults.html">Default and Override Labels:</a> Specifies what
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a user agent (e.g., filtering software) should do when multiple labels are
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available from the same service; Also suggests where filtering agents
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should look for self-labels if they do not arrive in or along-with a
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document.</li>
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</ol>
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<h2><a name="Developers"></a></h2>
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<h2>Resources for Developers of Software and Labeling Services</h2>
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<p>There is a low-volume mailing list, pics-interest@w3.org for developers and
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potential developers of PICS related products and services. To join this list,
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send email to pics-ask@w3.org and say why you're interested in joining. </p>
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<h3>Resources for Software Developers</h3>
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<p>The <a href="#Specs">technical specifications</a> above are the most
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important resource for developers. In addition:</p>
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<ul>
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<li>Free <a href="refcode/Parser/">Java implementation</a> of parsers for
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PICS labels, services, and rules, evaluator for PICSRules</li>
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<li><a href="http://www.w3.org/PICS/refcode/PICSLE/">PICSLE</a>, the PICS
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Label Editor, also written in Java, provided courtesy of <i><a
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href="http://www.watson.ibm.com/">IBM T.J. Watson Research
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Center.</a></i></li>
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<li><a href="http://www.ics.raleigh.ibm.com/WebTrafficExpress">IBM's
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PICS-compliant proxy server</a> makes it easy to set up a label bureau
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against which you can test clients.</li>
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<li><a href="http://www.w3.org/pub/WWW/PICS/extensions/">Protocol
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extensions.</a> These are extensions that people have defined using the
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extension mechanisms provided in the technical specifications.</li>
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<li><a href="http://www1.raleigh.ibm.com/pics/hints.html">Hints to
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implementors</a></li>
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<li>Various tools and free technical advice available from the <a
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href="http://www.si.umich.edu/~presnick/PICS-incubator/">PICS Application
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Incubator</a> project at the University of Michigan School of
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Information.</li>
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</ul>
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<h3>Resources for Labeling Service Developers</h3>
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<p>To start a new labeling service, you will need to take the following
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steps:</p>
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<ol>
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<li>Decide who will assign labels.
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<ul>
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<li>Web site operators who self-label <i>and/or</i></li>
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<li>A panel of raters that you recruit <i>and/or</i></li>
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<li>A computer program that analyzes the contents of materials and
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assigns labels</li>
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</ul>
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</li>
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<li>Decide the labeling vocabulary and criteria</li>
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<li>Express the labeling vocabulary and criteria according to the format
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specified in the <a
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href="http://www.w3.org/TR/REC-PICS-services">technical specification</a>.
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You can create this file from scratch, or you can fill out web forms at
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the <a href="http://www.si.umich.edu/~presnick/PICS-incubator/">PICS
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Application Incubator</a> and the file will be created for you.</li>
|
|
<li>Create the labels</li>
|
|
<li>Arrange for distribution of your labels
|
|
<ul>
|
|
<li>Give your labels to someone else who is running a PICS label bureau
|
|
<i>and/or</i></li>
|
|
<li>Run your own PICS label bureau <i>and/or</i></li>
|
|
<li>Convince web site operators to distribute the labels for their own
|
|
pages, either by putting them into HTML META tags or sending them
|
|
along with web pages.</li>
|
|
</ul>
|
|
</li>
|
|
</ol>
|
|
|
|
<p>The <a href="http://www.si.umich.edu/~presnick/PICS-incubator/">PICS
|
|
Application Incubator</a> project at the University of Michigan School of
|
|
Information will provide a limited amount of free technical consulting to
|
|
organizations that are considering establishing new labeling services.</p>
|
|
|
|
<h2><a name="Products"></a>Lists of PICS-compatible products and
|
|
services.</h2>
|
|
|
|
<p><b><a href="http://www.research.att.com/~lorrie/pubs/tech4kids/">Technology
|
|
Inventory</a></b> [broken link as of July 2005].
|
|
Lorrie Cranor and Paul Resnick. This inventory was first
|
|
distributed at the December 1997 Internet On-line summit: Focus on Children.
|
|
The on-line version was updated until the summer of 1999. It also lists some
|
|
products and services that are not PICS-compatible.</p>
|
|
|
|
<p>The following resource lists are being maintained by members of the PICS
|
|
developers' community. Contact the maintainer of each individual list with
|
|
additional links. The maintainers have all agreed to be fast and fair in
|
|
maintaining these lists (please send any unresolved complaints to
|
|
pics-ask@w3.org).</p>
|
|
<ul>
|
|
<li><a href="http://www.microsys.com/pics/">Client software</a>
|
|
[broken link as of July 2005] that reads
|
|
PICS labels.</li>
|
|
<li><a href="http://www1.raleigh.ibm.com/pics/servers.html">HTTP servers</a>
|
|
that distribute labels along with documents.</li>
|
|
<li><a href="http://www.n2h2.com/pics/proxy_servers.html">Proxy servers</a>
|
|
[broken link as of July 2005]
|
|
that perform filtering based on PICSRules.</li>
|
|
<li><a href="bureaus.htm">Label bureaus</a>: HTTP servers that distribute
|
|
third-party PICS labels through the PICS label bureau query protocol.</li>
|
|
<li><a href="raters.htm">Rating services</a></li>
|
|
<li><a href="http://www.xav.com/scripts/search/">Search engine</a> that can use PICS labels in its selection criteria</li>
|
|
<li><a href="http://www.getnetwise.org">more information</a> "for families
|
|
and caregivers" from <a
|
|
href="http://www.getnetwise.org/supporters.shtml">GetNetWise</a>
|
|
[broken link as of July 2005]</li>
|
|
</ul>
|
|
|
|
<h2><a name="Innovations"></a>Innovative Uses of PICS Labels</h2>
|
|
|
|
<p>The most common uses of PICS labels have been in filtering products that
|
|
block access to certain materials based on labels associated with those
|
|
materials. The <a
|
|
href="http://www.research.att.com/~lorrie/pubs/tech4kids/">technology
|
|
inventory</a>, however, identifies a range of other actions that can be taken
|
|
based on labels: suggest, search, inform, monitor/log, and warn.</p>
|
|
<ul>
|
|
<li>Inform: <a href="http://www.medcertain.org">med-PICS</a>; a collaboration
|
|
for critical appraisal of medical information on the Internet</li>
|
|
<li>Search: <a href="http://www.netshepherd.com">Net Shepherd and Alta Vista
|
|
offer filtered Internet search</a>
|
|
[broken link as of July 2005]</li>
|
|
<li>Inform: <a href="http://www.alexa.com">Alexa Internet</a> displays PICS
|
|
labels visually, but does not block access based on those labels.</li>
|
|
<li>Inform: The Test-a-URL feature created by the <a
|
|
href="http://www.si.umich.edu/~presnick/PICS-incubator/">PICS Application
|
|
Incubator</a> lets you see what labels have been assigned to any URL by
|
|
several different rating services. (A <a
|
|
href="http://cgi.pathfinder.com/netly/spoofcentral/censored/">similar
|
|
test-a-URL feature</a> is available for other, non PICS-based
|
|
services.)</li>
|
|
</ul>
|
|
|
|
<h2><a name="Authors"></a>Hints for Web Site Authors Who Want to
|
|
Self-Label</h2>
|
|
|
|
<p>Many authors and web site operators offer materials that they realize will
|
|
not be appropriate for all audiences. We encourage them to label their
|
|
materials to make it easier for filtering software to block access. As an
|
|
added inducement to labeling, we note that some future applications may use
|
|
labels for searching as well as filtering. Thus, labeling your site will make
|
|
it easier both for some audiences to avoid your site or documents and for
|
|
others to find you.</p>
|
|
|
|
<p>PICS is able to remain value-neutral by refusing to endorse any particular
|
|
labeling vocabulary. As a web site operator, you will not have that luxury.
|
|
You'll want to adopt one or more of the rating vocabularies that other sites
|
|
are using. You may want to use one of the <a
|
|
href="raters.htm#self">self-rating vocabularies</a>.</p>
|
|
|
|
<p>Once you have created a label, you will need to distribute it along with
|
|
your document(s). PICS has defined several ways to do that. The recommended
|
|
method, if your HTTP server allows it, is to insert an extra header in the
|
|
HTTP header stream that precedes the contents of documents that are sent to
|
|
web browsers. The correct format, as documented in the specifications, is to
|
|
include the two headers, Protocol and PICS-Label:</p>
|
|
|
|
<div class="header-example">
|
|
<p>HTTP/1.0 200 OK <br>
|
|
Date: Thu, 30 Jun 1995 17:51:47 GMT <br>
|
|
Last-modified: Thursday, 29-Jun-95 17:51:47 GMT <br>
|
|
Protocol: {PICS-1.1 {headers PICS-Label}} <br>
|
|
PICS-Label: <br>
|
|
(PICS-1.1 "http://www.gcf.org/v2.5" labels <br>
|
|
on "1994.11.05T08:15-0500" <br>
|
|
exp "1995.12.31T23:59-0000" <br>
|
|
for "http://www.greatdocs.com/foo.html" <br>
|
|
by "George Sanderson, Jr." <br>
|
|
ratings (suds 0.5 density 0 color/hue 1)) <br>
|
|
Content-type: text/html</p>
|
|
|
|
<p>...contents of foo.html...</p>
|
|
</div>
|
|
|
|
<p>The server can send these headers even if the browser has not specifically
|
|
request them.</p>
|
|
|
|
<p>The next best method is to run a label bureau at a specific location on
|
|
your server, as specified in a <a href="defaults.html">supplement</a> to the
|
|
PICS specs, distributing labels only for documents on your server.</p>
|
|
|
|
<p>If neither of these methods is not available to you, a simpler but more
|
|
limited method is to embed labels in HTML documents using a META tag. With
|
|
this method, you will be able to send labels only with HTML documents, not
|
|
with images, video, or anything else. You may also find it cumbersome to
|
|
insert the labels into every HTML document. Some browsers, notably Microsoft's
|
|
Internet Explorer versions 3 and 4, will download the root document for your
|
|
web server and look for a generic label there. For example, if no labels were
|
|
embedded in the HTML for this web page (they are), Internet Explorer would
|
|
look for a generic label embedded in the page at http://www.w3.org/ (generic
|
|
labels can be found there). Be sure to read the <a
|
|
href="defaults.html">supplement </a>for information on when specific labels
|
|
override generic labels and when they don't.</p>
|
|
|
|
<p>The following is a an example of the right way to embed a PICS label in an
|
|
HTML document:</p>
|
|
|
|
<h3>RIGHT!</h3>
|
|
<pre><head>
|
|
|
|
<META http-equiv="PICS-Label" content='
|
|
|
|
(PICS-1.1 "http://www.gcf.org/v2.5"
|
|
|
|
labels on "1994.11.05T08:15-0500"
|
|
|
|
until "1995.12.31T23:59-0000"
|
|
|
|
for "http://w3.org/PICS/Overview.html"
|
|
|
|
ratings (suds 0.5 density 0 color/hue 1))
|
|
|
|
'>
|
|
|
|
</head>
|
|
|
|
...contents of document here...</pre>
|
|
|
|
<p>The following is incorrect, because the label is in the body of the
|
|
document rather than in the HTML header (delimited by <head> and
|
|
</head>).</p>
|
|
|
|
<h3>WRONG!</h3>
|
|
<pre><head>
|
|
|
|
</head>
|
|
|
|
<META http-equiv="PICS-Label" content='
|
|
|
|
(PICS-1.1 "http://www.gcf.org/v2.5"
|
|
|
|
labels on "1994.11.05T08:15-0500"
|
|
|
|
until "1995.12.31T23:59-0000"
|
|
|
|
for "http://w3.org/PICS/Overview.html"
|
|
|
|
ratings (suds 0.5 density 0 color/hue 1))</pre>
|
|
<pre> '>
|
|
|
|
...contents of document here...</pre>
|
|
|
|
<p>It is OK to include more than one META tag in a single HTML document, so
|
|
you can provide labels according to several services. There also is a way to
|
|
combine several labels into a single label list. See the <a
|
|
href="#Specs">technical specifications</a> for details.</p>
|
|
|
|
<h2><a name="RDF">RDF</a></h2>
|
|
|
|
<p>Separate W3C working groups are developing a new label format, called RDF;
|
|
the Resource Description Framework, based on XML. <a
|
|
href="/TR/REC-rdf-syntax">RDF labels</a> will be able to express everything
|
|
that PICS labels can express, but will also permit string and structured
|
|
values, and some other nifty features. The latest information on this
|
|
available at <a href="http://www.w3.org/RDF">http://www.w3.org/RDF.</a></p>
|
|
|
|
<h2><a name="FAQ"></a>Frequently Asked Questions</h2>
|
|
|
|
<p>A separate <a href="http://www.w3.org/2000/03/PICS-FAQ">PICS FAQ</a>
|
|
document is available, offering answers to a number of common questions about
|
|
PICS. In addition a <a href="PICS-FAQ-980126.html">separate FAQ</a> addresses
|
|
intellectual freedom implications of PICS.</p>
|
|
<hr>
|
|
<address>
|
|
Comments to <a href="mailto:PICS-ask@w3.org">PICS-ask@w3.org</a>.
|
|
</address>
|
|
<address>
|
|
<a href="../Help/Webmaster.html">Webmaster</a>
|
|
</address>
|
|
<address>
|
|
$Date: 2009/11/20 13:45:12 $ by $Author: phila $
|
|
</address>
|
|
|
|
<p class="copyright"><a rel="Copyright"
|
|
href="/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © 1997-2003
|
|
<a href="/"><acronym
|
|
title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a
|
|
href="http://www.lcs.mit.edu/"><acronym
|
|
title="Massachusetts Institute of Technology">MIT</acronym></a>, <a
|
|
href="http://www.ercim.org/"><acronym
|
|
title="European Research Consortium for Informatics and
|
|
Mathematics">ERCIM</acronym></a>, <a
|
|
href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved.
|
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|
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W3C <a
|
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href="/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a
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href="/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>, <a
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rel="Copyright" href="/Consortium/Legal/copyright-documents">document
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|
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and <a rel="Copyright" href="/Consortium/Legal/copyright-software">software
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licensing</a> rules apply. Your interactions with this site are in
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