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204 lines
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<title>Term-centric Semantic Web Vocabulary Annotations</title>
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<p><a href="http://www.w3.org/"><img src="http://www.w3.org/Icons/w3c_home" alt="W3C" height="48" width="72" /></a></p>
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<h1 id="main">Term-centric Semantic Web Vocabulary Annotations</h1>
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<h2 class="no-num no-toc" id="w3c-doctype">(Editor's Draft of a potential) W3C Interest Group Note 31 December 2009</h2>
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<dl>
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<dt>This version:</dt>
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<dd><a href="http://www.w3.org/TR/2009/NOTE-vocabstatus-2009@@@/">http://www.w3.org/TR/2009/NOTE-vocabstatus-2009@@/</a></dd>
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<dt>Latest version:</dt>
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<dd><a href="http://www.w3.org/TR/vocabstatus/">http://www.w3.org/TR/vocabstatus/</a></dd>
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<dt>Editor:</dt>
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<dd><a href="http://danbri.org/">Dan Brickley</a>, Vrije Universiteit Amsterdam <danbri@danbri.org></dd>
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<dt>Contributors:</dt>
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<dd>Leigh Dodds, Talis</dd>
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<dd>Libby Miller, BBC</dd>
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</dl>
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</div>
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<p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © 2009 <a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a href="http://www.csail.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. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.</p>
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<hr title="Separator for header" />
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<h2 class="notoc" id="abstract">Abstract</h2>
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<p>
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Many Semantic Web vocabularies (dictionaries of terms expressed using RDFS or OWL technology) evolve gradually, based on implementor feedback, deployment dynamics and a desire to start by
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solving small problems first. This Note describes and documents a basic vocabulary - initiated in the FOAF project - that was created to provide a way of annotating RDF terms (classes and properties) with simple information about their status.
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</p>
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<h2 id="status">Status of This Document</h2>
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<p><strong>This is a pre-draft from Dan Brickley</strong>, attempting to capture something of the thinking behind the vocab-status-ns work. Not yet reviewed by Leigh and Libby, and changing at random.</p>
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<p><em>This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the <a href="http://www.w3.org/TR/">W3C technical reports index</a> at http://www.w3.org/TR/.</em></p>
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<p>This W3C Interest Group Note was created to document a vocabulary that has been used for several years in documenting the status of RDF vocabulary terms.</p>
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<p>The document was produced by participants of the W3C <a href="http://www.w3.org/2001/sw/interest/">Semantic Web Interest Group</a> part of the <a href="http://www.w3.org/2001/sw/">W3C Semantic Web Activity</a> (<a href="http://www.w3.org/2006/07/swig-charter.html">see charter</a>). Comments may be sent to the <a href="http://lists.w3.org/Archives/Public/semantic-web/">publicly archived</a> <a href="mailto:semantic-web@w3.org">semantic-web@w3.org</a> mailing list. While it does not represent the consensus of all members of the Interest Group, it does improve the documentation of a namespace used to annotate a very widely used vocabulary, ie. FOAF. As such it is offered here for wider discussion and potential improvements.
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</p>
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<p>Publication as an Interest Group Note does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.</p>
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<hr />
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<div class="toc">
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<h2 id="contents">Table of Contents</h2>
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<ul class="toc">
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<li class="tocline1"><a href="#introduction">1 Introduction</a></li>
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</ul>
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</div>
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<h3 id="appendices">Appendices</h3>
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<ul class="toc">
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<li class="tocline2"><a href="#references">A References</a></li>
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<li class="tocline2"><a href="#acknowledgements">B Acknowledgements</a></li>
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</ul>
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<hr />
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<h2 id="introduction">1 Introduction</h2>
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<p>
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The evolution of descriptive computer languages within the World-Wide Web is an ongoing challenge. W3C's RDF technology does not attempt to solve such problems, but it does present a distinctive environment for deploying
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descriptive vocabularies. This Note documents some specific documentation and versioning techniques originated in the Friend of a Friend (FOAF) project, and which have subsequently been adopted for other RDF/OWL vocabularies. The basic idea is that RDF vocabularies can be versioned "in-place", rather than moving to a new namespace URI every time a vocabulary is extended or improved, we can tag each term in the vocabulary with information indicating its status.
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</p>
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<h2 id="history">2 History</h2>
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<p>
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The earliest RDF representations of <a href="http://www.dublin-core.org/">Dublin Core</a> metadata embedded a version number in their URI: initially "1.0" (at http://purl.org/dc/elements/1.0/) and after some modest changes, "1.1" (at http://purl.org/dc/elements/1.1/). The earliest FOAF (originally as "RDFWebRing", and then "RDFWeb") experiments also included a version number "0.1" in the namespace URI - i.e. http://xmlns.com/foaf/0.1/ - where the low number was intended to indicate the tentative and exploratory nature of this early work. Other early RDF vocabularies including <a href="http://web.resource.org/rss/1.0/spec">RSS 1.0</a> - at http://purl.org/rss/1.0/ - also adopted a similar approach to selecting namespace URIs. In each case, there are lessons to be learned from the approach taken to modularity and versioning.
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</p>
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<p>
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The early RDF representations of Dublin Core, RSS 1.0 and FOAF all began by treating the entire vocabulary as the primary unit of versioning, and with a general assumption
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that any major changes would involve a wholesale move to a new namespace URI. With Dublin Core, this assumption was tested in practice: changes to some of the original
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definitions were considered at the time significant enough to justify moving to a new identifier for the entire set of terms. The awkward practicalities of migrating from DC "1.0" to
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"1.1" in a global, distributed and decentralised environment were one of the major considerations that led to the RDFWeb/FOAF adoption of 'in-place' updates. Unfortunately this
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was not fully appreciated at the time FOAF's original namespace URI was selected, and the vocabulary has retained the "0.1" version number in its URI ever since. RSS1, by contrast,
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has never evolved its RDF representation: the rss-dev group that produced it was effectively disbanded shortly afterwards, and the RSS syndication community remained divided
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between a non-RDF RSS 2.0, the subsequently-undeveloped RSS1 work and the IETF-standard Atom initiative. The RSS1 initial design however did emphasise a particular approach to
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modularity: that of using numerous namespaces together, rather than having a more monolithic approach in which a variety of problems are addressed through a single integrated vocabulary.
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The RSS 1.0 documents list <a href="http://web.resource.org/rss/1.0/modules/proposed.html">over twenty</a> proposed modules; in addition to the general background assumption that
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arbitrary RDF vocabularies could be mixed-in as necessary.
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</p>
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<p>
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The earliest FOAF vocabulary was offered as a "utility vocabulary" within the RDFWeb project, and its documentation was heavily driven by implementation experiments. In fact
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many of the spelling and stylistic inconsistencies in the names for FOAF terms came from the habit of testing things in real published RDF/XML files before documenting them in the central specification.
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The FOAF spec was as a result always framed in the role of a dictionary, documenting the terms used in published FOAF files. The vocabulary defined here was designed to serve
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a practical need: that of documenting work-in-progress vocabulary without confusing users and implying stability merely by some term appearing in the FOAF spec.
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</p>
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<h2 id="vocab"><b>B </b>Vocab</h2>
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<p>The 'Vocabulary Status Vocabulary', as it is informally known, contained only three properties (from 2003-2009). And of these, only one was widely used: vs:term_status, vs:moreinfo, and vs:userdocs.</p>
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<p>
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The main property, vs:termstatus takes simple string values. From 2003-2009 these were documented as being 'unstable', 'testing' and 'stable'. Values of 'deprecated' were
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also noted "in the wild". In 2009 the vocabulary documentation was updated to introduce a new value, 'archaic', and to indicate that the value space for the property is open-ended.
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</p>
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<h3>vs:term_status</h3>
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<p>
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The vs:term_status property is designed to provide a simple, intuitive labelling of an RDF class or property into one of a few limited categories. As such it might more
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properly have been modelled using URI values rather than strings. The following definitions are ad-hoc, but should broadly correspond to their deployed usage.
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</p>
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<p>
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The exact meaning of stable/unstable/testing/archaic will vary from project to project, since the maintainers of RDF vocabularies may have quite varied maintainance and
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vocabulary development models. Other annotations might capture more detail; these term_status values serve to give a general overview. The values described here have a
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bias towards their use with FOAF, but are also fairly general.
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</p>
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<dl>
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<dt>'unstable'</dt>
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<dd>The meaning, deployment practices, documentation (or important associated software/services) associated with this term are liable to change arbitrarily at some point in the future. They may not, but stability is not guaranteed. Use with caution.</dd>
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<dt>'testing'</dt>
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<dd>The meaning, deployment practices, documentation and general understanding of this term are approaching some stability, but changes are still possible due to implementation experience or other unanticipated factors.</dd>
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<dt>'stable'</dt>
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<dd>The term is relatively stable, and its documentation and meaning are not expected to change substantially.</dd>
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<dt>'archaic'</dt>
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<dd>This term is marked as old-fashioned; although used, it is not considered typical of current best practice and alternative expressions may be preferable.</dd>
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</dl>
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<h2 id="usage">Example Usage</h2>
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<p>An unsorted collection of usage examples follow.</p>
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<pre>
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http://dbtune.org/onto/doc/event.rdf (defines vs:term_status as AnnotationProperty)
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http://uriplay.org/spec/ontology/latest.rdf
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http://motools.sourceforge.net/doc/last-fm.rdf
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http://digitalbazaar.com/media/video (in RDFa syntax)
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http://digitalbazaar.com/media
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http://digitalbazaar.com/commerce
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http://sw.deri.org/2005/08/conf/cfp.owl
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http://www.mindswap.org/2003/owl/foaf (OWLier version of FOAF?)
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http://vamp-plugins.org/rdf/
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http://www.bbc.co.uk/ontologies/programmes/2008-02-28.rdf
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http://xam.de/ns/os/opensource.rdfs
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http://data.semanticweb.org/ns/swc/swc_2009-02-27.rdf (uses 'deprecated')
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http://scot-project.org/scot/ns
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http://xmlns.com/wot/0.1/index.rdf
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http://vocab.org/review/terms.rdf (actually has some 'stable'; pretty rare!)
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http://danja.talis.com/xmlns/rev_2007-11-09/review.rdf (related?)
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http://www.w3.org/ns/auth/rsa.rdf
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http://www.w3.org/ns/auth/cert.rdf
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http://motools.sourceforge.net/doc/audio_features.rdf
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http://www.foafrealm.org/xfoaf/0.1/index.rdf
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http://www.w3.org/2004/02/skos/extensions.rdf
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http://bibotools.googlecode.com/svn/bibo-ontology/tags/1.2/bibo.xml
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http://musicontology.com/musicontology.rdfs
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http://www.ldodds.com/schemas/book/
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http://b4mad.net/ns/foaf-ext/index.rdf
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http://www.xs4all.nl/~foz/enclosures.rdf (also has 'deprecated')
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http://umbel.org/umbel/umbel.rdf (no content currently)
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http://projects.mi.fu-berlin.de/semweb/webrdf/ (server error)
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http://www.holygoat.co.uk/owl/redwood/0.1/tags/
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http://www.madore.org/~david/meta.rdf
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http://schemacache.test.talis.com/Properties/.rdf (reminds me - can
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you get some stats from schemacache?)
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http://www.kanzaki.com/ns/dliser.rdf ('An OWL DLiser. Declarations of
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Classes and Properties that would be used in some ontologies for
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documentation purpose. With owl:imports this file, the parent ontology
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will be valid OWL DL/Lite.')
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http://www.kanzaki.com/ns/wordmap
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http://www.kanzaki.com/ns/sitemap.rdf
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http://ccdb.ucsd.edu/SAO/1.0/SAO.owl (defined but not used)
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</pre>
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<h2 id="usage">Open Issues</h2>
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<p>Issues with this document, and with the underlying vocabulary.</p>
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<ul>
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<li>todo: add RDFa to this note, so that the rdf/xml for the namespace can be derrived from it</li>
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<li>propose a successor to vs:term_status that takes URI values</li>
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<li>investigate adding AnnotationProperty construct, and note other mechanisms from OWL eg. deprecated property / class</li>
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<li>Use footnotes / references rather than direct links?</li>
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<li>Propose dropping the un-used properties?</li>
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<li>Check for other values for term_status 'in the wild'</li>
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<li>Organize and write the 'usage examples' section better, rather than giving ugly url dump</li>
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<li>Better DC ref and discussion - check with Tom Baker</li>
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</ul>
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<h2 id="acknowledgements"><b>B </b>Acknowledgements</h2>
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<p>@@@</p>
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