Special properties (declarative)

From semantic-mediawiki.org

This help page lists the declarative special properties. Declarative special properties are used to define or declare the behaviour of properties on their properties pages, i.e. they can only be used in namespace "Property". Starting with Semantic MediaWiki 3.0.0Released on 11 October 2018 and compatible with MW 1.27.0 - 1.31.x. error messages1 will be issued if a declarative special property is used in other namespaces than that.2

The following table gives an overview of all 18 visible special properties provided by Semantic MediaWiki:

NameDescriptionHelp pageSinceKey
Allows valueLists one permissible value for a propertySpecial property "Allows value"1.0
Corresponds toGives the conversion factor for some unit of a physical quantity and the possible names for that unitSpecial property "Corresponds to"1.0
Display unitsSpecifies the a comma-separated list of units or formats that a property should use in displaySpecial property "Display units"1.0
Equivalent URIMarks a page in the wiki as having a well-known meaning beyond this wiki, in an external URISpecial property "Equivalent URI"1.0
Has typeAssigns a datatype to a propertySpecial property "Has type"1.0
Imported fromAllows users to reuse elements of external vocabularies directly within the wikiSpecial property "Imported from"1.0
Provides serviceAdds service links to propertiesSpecial property "Provides service"1.0
Subproperty ofLets you indicate that one property is a subproperty of anotherSpecial property "Subproperty of"1.0
Has fieldsDefines a short list of fields with a fixed type and order for datatype RecordSpecial property "Has fields"1.5.0
Subcategory ofLets you explicitly indicate that one category is a subcategory of anotherSpecial property "Subcategory of"1.5.0
Allows patternPattern to match a permissible valueSpecial property "Allows pattern"2.4.0
Display precision ofAllows to define the display precision in digitsSpecial property "Display precision of"2.4.0
Has property descriptionAdds localizable context help to propertiesSpecial property "Has property description"2.4.0
Has uniqueness constraintAllows to restrict value annotation to be uniqueSpecial property "Has uniqueness constraint"2.4.0
Allows value listAdds a reference to a list of permissible values for a propertySpecial property "Allows value list"2.5.0
External formatter URIDeclares an external URL with placeholders $1, $2Special property "External formatter URI"2.5.0
Has preferred property labelAdds localizable labels to a propertySpecial property "Has preferred property label"2.5.0
Change propagationHolds the new property specification of a property or category pageSpecial property "Change propagation"3.0.0

Conversely all special properties not listed here are not declarative.

Special property "Subcategory of"Lets you explicitly indicate that one category is a subcategory of another and special property "Change propagation"Holds the new property specification of a property or category page can also be used in namespace "Category".


  1. ^  Semantic MediaWiki: Sandbox example sb:smw:2820
  2. ^  Semantic MediaWiki: GitHub issue gh:smw:2820