Help:Special property "Allows value"

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This documentation page applies to all SMW versions from 1.0 to 1.5.6.
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Help:Special property Allows value en 1.0 1.5.6

Allows value
Lists one permissible value for a property
Further Information
Provided by: Semantic MediaWiki
Added: 1.0
Removed: still in use
Alias: has no alias
Is optional: no
Label: not specified
Focus: not specified
In this wiki: Property:Allows value

The Allows value property is a special property in Semantic MediaWiki with a built-in meaning: it lists one permissible value for a property.

You can use this special property with a property of any datatype to limit its possible values. For example, the page for a Problem severity property might contain:

 [[Allows value::Enhancement]]
 [[Allows value::Trivial]]
 [[Allows value::Minor]]
 [[Allows value::Normal]]
 [[Allows value::Major]]
 [[Allows value::Critical]]

Ordered properties

Enumerating several Allows value does not put the possible values of a property in that order. Properties of datatype String will still sort in alphabetical order. You can ensure that alphabetical sort order is appropriate by using a prefix, for example:

 [[Allows value::a - Enhancement]]
 [[Allows value::b - Trivial]]
 [[Allows value::c - Minor]]

Thus you can query for greater-than-or-equal or less-than-or-equal values, for example [[property name::<c-Minor]]

You can also create a property of datatype Number and give it allowed values that are "pseudo-numbers", for example:

 [[Allows value::1 - Low]]
 [[Allows value::2 - Medium]]
 [[Allows value::2 - Middling]]

SMW's number datatype ignores the "- description" after the number. This gives the set of properties a numerical order and lets you define two values as equivalent.

See the property page Allows value to see which pages use this special property on this wiki.