Hey folks :)
We just enabled statements on properties. You can for example use this to: * describe mappings to other projects' vocabularies * indicate constraints for the usage of this property (currently stored in templates on the talk page of the property) * store information about where this property is used in other projects to make sure they can be notified when major changes are made to how the property is used * provide links to extensive documentation about and showcases for the usage of this property * store patterns for how an identifier should be expanded to form a proper URL * ...
Some notes: * You can't yet make statements linking to other properties to for example indicate that property X is the inverse of property Y. We are adding a new datatype for that. It'll come soon. The ticket for that is https://phabricator.wikimedia.org/T75302 * Constraint violation reports currently don't take these statements into account. They will continue to use the templates on the property's talk page. A team of students is currently working on overhauling the whole constraint system. It'll take them a while still though.
Unrelated but also important for you to know: If a page is deleted on Wikipedia/Commons/... that has a sitelink in an item on Wikidata that link will be removed automatically now.
Cheers Lydia