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:

Name Description Help Added Key
Allows value Lists one permissible value for a property help page 1.0
Corresponds to Gives the conversion factor for some unit of a physical quantity and the possible names for that unit help page 1.0
Display units Specifies a comma-separated list of units or formats that a property should use in display help page 1.0
Equivalent URI Marks a page in the wiki as having a well-known meaning beyond this wiki, in an external URI help page 1.0
Has type Assigns a datatype to a property help page 1.0
Imported from Allows users to reuse elements of external vocabularies directly within the wiki help page 1.0
Provides service Adds service links to properties help page 1.0
Subproperty of Lets you indicate that one property is a subproperty of another help page 1.0
Has fields Defines a short list of fields with a fixed type and order for datatype Record help page 1.5.0
Subcategory of Lets you explicitly indicate that one category is a subcategory of another help page 1.5.0
Allows pattern Pattern to match a permissible value help page 2.4.0
Display precision of Allows to define the display precision in digits help page 2.4.0
Has property description Adds localizable context help to properties help page 2.4.0
Has uniqueness constraint Allows to restrict value annotation to be unique help page 2.4.0
Allows value list Adds a reference to a list of permissible values for a property help page 2.5.0
External formatter URI Declares an external URL with placeholders $1, $2 help page 2.5.0
Has preferred property label Adds localizable labels to a property help page 2.5.0
Change propagation Holds the new property specification of a property or category page help page 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".

See also[edit]

Octocat.png"TypesRegistry.php" – The general characteristics of a special property are defined here.


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