"Allows value" is a predefined property that can define a list of permissible values to restrict value assignments for a property and is provided by Semantic MediaWiki. This property is pre-deployed (also known as special property) and comes with additional administrative privileges but can be used just like any other user-defined property.
CSDMS 2018 annual meeting - Geoprocesses, geohazards +, CTSP: Coupling of Tectonic and Surface Processes +, CSDMS 2017 annual meeting: Modeling Coupled Earth and Human Systems - The Dynamic Duo +, …