Help:Property constraints portal/Citation needed

citation needed constraint (Q54554025) specifies that statements for a certain property should have at least one reference. For example, this could be used on properties likely to be challenged.

It doesn’t matter what the references look like, as long as at least one reference exists.

This constraint can only be checked on the main value of a statement; if any other constraint scope (P4680) is specified, an error is reported.

Possible actions

There are several possible ways to address a violation of this constraint:

• The most likely case is that a reference should be added. See Help:Sources for when and how to add references. For properties using this constraint, it's unlikely that the mere addition of imported from Wikimedia project (P143) is considered sufficient.
• It’s possible that the statement is a rare, but legitimate exception to the constraint, and nothing should be done.

Parameters

This constraint does not have any qualifier parameters.