Special properties

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This page describes the 46 special properties that are built-in to Semantic MediaWiki (SMW). They are needed to make the system work. They appear in a page's factbox, on special page "Properties"Lists properties and displays their usage and on special page "Browse"Shows all properties and their values annotated to a page in italic. Since Semantic MediaWiki 1.4.0Released on 21 November 2008 and compatible with MW 1.13.x - 1.16.x., special properties can be used in browsing interfaces and Inline queries just like all other properties. Also see the help page Properties and types for more information.

Special properties may also be provided by extensions to Semantic MediaWiki like, e.g. extension "Semantic Extra Special Properties"Adds some extra special properties to all pages or extension "Semantic Cite"Provides a simple way of organizing citation resources with the help of semantic annotations., etc. These however are currently not being documented here.

The names and aliases of special properties are reserved and cannot be used for other properties. Additionally special properties should only be used according to their documented purpose! It is not necessary to create pages for special properties. They will perform their special behavior even if your wiki does not have a property page for it.


The following table gives an overview of all 46 special properties provided by Semantic MediaWiki:
NameDescriptionHelp pageSinceKey
Allows valueLists one permissible value for a propertyHelp:Special property "Allows value"1.0
Corresponds toGives the conversion factor for some unit of a physical quantity and the possible names for that unitHelp:Special property "Corresponds to"1.0
Display unitsSpecifies the a comma-separated list of units or formats that a property should use in displayHelp:Special property "Display units"1.0
Equivalent URIMarks a page in the wiki as having a well-known meaning beyond this wiki, in an external URIHelp:Special property "Equivalent URI"1.0
Has typeAssigns a datatype to a propertyHelp:Special property "Has type"1.0
Imported fromAllows users to reuse elements of external vocabularies directly within the wikiHelp:Special property "Imported from"1.0
Provides serviceAdds service links to propertiesHelp:Special property "Provides service"1.0
Subproperty ofLets you indicate that one property is a subproperty of anotherHelp:Special property "Subproperty of"1.0
Modification dateHolds a fixed value that corresponds to the date of the last modification of each pageHelp:Special property "Modification date"1.4.0
Has improper value forAlerts in case the assigned value to a property is invalidHelp:Special property "Has improper value for"1.4.2
Has fieldsDefines a short list of fields with a fixed type and order for datatype RecordHelp:Special property "Has fields"1.5.0
Subcategory ofLets you explicitly indicate that one category is a subcategory of anotherHelp:Special property "Subcategory of"1.5.0
Creation dateHolds a fixed value that corresponds to the date of the first revision of each pageHelp:Special property "Creation date"1.7.0
Has subobjectHolds the subobjects set on a pageHelp:Special property "Has subobject"1.7.0
Is a new pageHolds a value marking a page as being new or notHelp:Special property "Is a new page"1.7.1
Last editor isHolds the page name of the user who created the last page revisionHelp:Special property "Last editor is"1.7.1
Has queryLinks a page to the subobject created by a query recording its profileHelp:Special property "Has query"1.8.0
Query depthHolds the value of the property depth of a queryHelp:Special property "Query depth"1.8.0
Query formatHolds the name of the result format used in a queryHelp:Special property "Query format"1.8.0
Query sizeHolds the value of the number of conditions in a queryHelp:Special property "Query size"1.8.0
Query stringHolds the conditions of the query as a stringHelp:Special property "Query string"1.8.0
Query durationHolds the value of the duration a query took to executeHelp:Special property "Query duration"1.9.0
MIME typeHolds the MIME type of an uploaded fileHelp:Special property "MIME type"1.9.1
Media typeHolds the Media type of an uploaded fileHelp:Special property "Media type"1.9.1
Allows patternPattern to match a permissible valueHelp:Special property "Allows pattern"2.4.0
Display precision ofPrecision in digitsHelp:Special property "Display precision of"2.4.0
Display title ofHolds a specific denote title for an entityHelp:Special property "Display title of"2.4.0
Has processing errorHolds a "container" with further information about a problem and allows to explore it.Help:Special property "Has processing error"2.4.0
Has processing error textContains a textual description of an error which occurred during the processing of a page.Help:Special property "Has processing error text"2.4.0
Has property descriptionAdds localizable context help to propertiesHelp:Special property "Has property description"2.4.0
Has uniqueness constraintAllows to restrict value annotation to be uniqueHelp:Special property "Has uniqueness constraint"2.4.0
Language codeHandles BCP47 conform language codes specifying the language of the annotated textHelp:Special property "Language code"2.4.0
Allows value listAdds a reference to a list of permissible values for a propertyHelp:Special property "Allows value list"2.5.0
External formatter URIDeclares an external URL with a place holder $1Help:Special property "External formatter URI"2.5.0
External identifierSpecifies an external identifierHelp:Special property "External identifier"2.5.0
Has preferred property labelAdds localizable labels to a propertyHelp:Special property "Has preferred property label"2.5.0
Is edit protectedStores the status of an edit restriction of a pageHelp:Special property "Is edit protected"2.5.0
Query parametersHolds the parameters a query used to select its outputHelp:Special property "Query parameters"2.5.0
Query sourceHolds the identifier of an alternative (e.g. remote) query sourceHelp:Special property "Query source"2.5.0
Change propagationHolds the new property specification of a property or category pageHelp:Special property "Change propagation"3.0.0
Query scodeHolds the status code a query uses to define its internal stateHelp:Special property "Query scode"3.0.0

See also

Special properties can also be classified according to a certain behaviour they have or allow for. See the following help pages for further information:

Applying styles

In case you would like to make special properties easier to be identified in the factbox, on special page "Properties"Lists properties and displays their usage and on special page "Browse"Shows all properties and their values annotated to a page just add, e.g. the following CSS code to the MediaWiki:Common.css page.

.smwbuiltin a,
.smwbuiltin a.new {
    color: #ff8000;
NoteNote: Special properties are are already printed in italics prior to the extra formatting mentioned here.