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If you believe you were blocked by mistake, you can find additional information and instructions in the <a href="https://meta.wikimedia.org/wiki/Special:MyLanguage/No_open_proxies" class="extiw" title="m:Special:MyLanguage/No open proxies">No open proxies</a> global policy. </p> Otherwise, to discuss the block please <a href="https://meta.wikimedia.org/wiki/Steward_requests/Global" class="extiw" title="m:Steward requests/Global">post a request for review on Meta-Wiki</a>. You could also send an email to the <a href="https://meta.wikimedia.org/wiki/Special:MyLanguage/Stewards" class="extiw" title="m:Special:MyLanguage/Stewards">stewards</a> <a href="https://meta.wikimedia.org/wiki/Special:MyLanguage/VRT" class="extiw" title="m:Special:MyLanguage/VRT">VRT</a> queue at <kbd>stewards@wikimedia.org</kbd> including all above details.</div></div><hr /> <p>You can view and copy the source of this page. </p><textarea readonly="" accesskey="," id="wpTextbox1" cols="80" rows="25" style="" class="mw-editfont-monospace" lang="en" dir="ltr" name="wpTextbox1"><languages/> {{Help:Property constraints portal/Header constraint type}} [[File:Pictogram voting not equal.svg|thumb]] <translate> <tvar|q21502410>{{Q|Q21502410}}</> specifies that values for this property should be unique across all of Wikidata, and no other entity should have the same value in a statement for this property.  Almost all (external) identifier properties have such a constraint, since an <tvar|p212>{{P|P212}}</> or <tvar|p646>{{P|P646}}</> should uniquely identify an entity. Other examples include <tvar|p163>{{P|P163}}</> and <tvar|p85>{{P|P85}}</>. Also <tvar|p373>{{P|P373}}</> should be unique because those categories typically have a unique Commons sitelink.  Properties with this constraint usually also have <tvar|q19474404>{{Q|Q19474404}}</>.  If no <tvar|p4680>{{P|4680}}</> is specified, this constraint is only checked on the main value of a statement.  A qualifier can be defined as <tvar name="p4155">{{P|4155}}</tvar>. This allows the same value on multiple entities as long as the separator qualifier is different. == Possible actions ==   There are several possible ways to address a violation of this constraint:</translate> * <translate> It’s possible that the conflicting items are duplicates and should be merged.</translate> * <translate> It’s possible that the property value is erroneous on one of the conflicting items (e. g. a typo, accidentally transposed digits, etc.) and should be fixed.</translate> * <translate> It is possible that a <tvar name="p4155">{{P|P4155}}</tvar> (or several of them) should be defined for the constraint, to declare that multiple items sharing a value are acceptable as long as they have certain different qualifiers.</translate> * <translate> It’s possible that the conflicting items are a rare, but legitimate exception to the constraint, and nothing should be done.</translate> <translate> == Parameters ==   This constraint has one optional parameter: </translate> ;<translate> <tvar name="p4155">{{P|P4155}}</tvar>: Contains the separators. May contain one or more properties. If specified, multiple statements with the same value do not constitute a violation of this constraint as long as they have different qualifiers for the properties specified here.</translate> <translate> == Example ==  </translate> {{Statement+ |P={{P-|P2302}} |V={{Q-|Q21502410}} |reference=close }} <translate> == Template ==   When the constraint is set to the property, the following template is automatically displayed in the property talk page. The template is created by [[Module:Constraints]] using [[Template:Constraint]], invoked from [[Template:Property documentation]]. Translations are defined at [[Module:i18n/constraints]].</translate> {{#invoke:Constraints|extractIndividualConstraintTemplate|id=P236|constraint_type=Q21502410}} <translate> == Exceptions ==   Cases where uniqueness should or could be evaluated differently and ways to handle such exceptions: </translate> *<translate> list exceptions as such on property constraints: available <tvar name="constraintparameter"><ref>[[Help:Property_constraints_portal#Constraint_parameters]] → {{P|2303}}</ref></tvar></translate> *<translate> indicate that an identifier is shared with another item: not available <tvar name="separator"><ref> [[Help_talk:Property_constraints_portal/Archive_1#separator_for_distinct_values_constraint]]</ref></tvar></translate> *<translate> indicate that an identifier was reassigned: not available</translate> *<translate> distinct best value constraint: not available <tvar name="distinctbest"><ref>[[Wikidata_talk:WikiProject_property_constraints/Archive_2#Distinct_best_value_constraint]]</ref></tvar></translate> *<translate> distinct case insensitive: not available, handling attempted by normalizing values <tvar name="caseinsensitive"><ref>[[Wikidata_talk:WikiProject_property_constraints/Archive_2#Distinct_case-insensitive_values]]</ref></tvar></translate> *<translate> distinct value including uses in references: available <tvar name="constraintparameter2"><ref>[[Help:Property_constraints_portal#Constraint_parameters]] → {{P|4680}}</ref></tvar></translate> *<translate> define uniqueness per namespace: not available <tvar name="pernamespace"><ref>[[Help talk:Property constraints portal/Unique value#Unique value per namespace]]</ref></tvar></translate> *<translate> define uniqueness per entity type (e.g. lexeme and item): not available</translate> <translate> == Lists ==   Lists of properties which are set distinct values constraint.</translate> * [[:Category:Properties with single value constraints]] * [https://query.wikidata.org/#SELECT%20%3FWikiData_property_%20%3FWikiData_property_Label%20%3FWikiData_property_Description%20%3FWikiData_property_AltLabel%20%0AWHERE%20%7B%0A%09%3FWikiData_property_%20wdt%3AP2302%20wd%3AQ21502410%20.%0A%09SERVICE%20wikibase%3Alabel%20%7B%20bd%3AserviceParam%20wikibase%3Alanguage%20%22%5BAUTO_LANGUAGE%5D%2Cen%22.%20%7D%0A%7D SPARQL query] - {{SPARQL advice}} {{Property constraints}} <translate> == Notes ==  </translate> {{reflist}} {{Translation categories|category=Help:Properties}} {{#ifeq:{{FULLPAGENAME}}|Help:Property constraints portal/Unique value|[[Category:Properties with unique value constraints|*]]}} </textarea><div class="templatesUsed"><div class="mw-templatesUsedExplanation"><p>Templates used on this page: </p></div><ul> <li><a href="/wiki/Template:Constraint" title="Template:Constraint">Template:Constraint</a> (<a href="/w/index.php?title=Template:Constraint&action=edit" 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