Help:Properties

From Constant Noble

The definition below comes from the 2008 version of Semantic MediaWiki's page on properties; much of this help page is loosely inspired by the text there.

In Semantic MediaWiki, a property gives machine-processable description of some feature of an object, such as its weight, size, location, or its owner. The property is written as an annotation in the article about the object that it describes.

And, as Referata's help page once stated:

[Properties are t]he basic building blocks of any semantic site.

In the case of [[Property::PageName]], for instance, SMW assumes the link "PageName" has its own article or page in the wiki site, via the help of the default Page datatype. By inserting Property:: before a regular MediaWiki link, the editor helps to explain why one page links to another.

This is different from the MediaWiki engine's normal link scheme of [[Namespace:PageName]].

In earlier versions of Semantic MediaWiki, properties were called relations and attributes, depending on their use.

Namespace and pages

Properties are given their own namespace in SMW-enabled sites, such as the ones that Referata hosts. Examples of such pages as apply here include Property:Morpheme name, Property:IPA syllable, and Property:Affix type.

Creating pages for every property is necessary, as all should be defined by the type stated with {{property type}}.

Special properties

SMW has some built-in properties that cannot be modified by editors, nor can be made for their own use. Two of these are Has type, for specifying types, and Allows value, for specifying default values.

Templates

The {{pl}} and {{wpl}} templates make use of property links on this wiki. {{pl}} enables linkage to wiki-wide pages where applicable, and {{wpl}} creates links to Wikipedia pages.

Another template, {{tpl}}, is found in templates that use it, and links to the property page that its parameter refers to.

Querying

Properties also prove useful on Special:Ask, where they can be typed in the "Additional printouts (optional)" box like this: ?Population.