Specifies the name of the column or columns that are a unique
    key or primary key or in the referenced table. When the
    REFERENCES clause is used as a table constraint, the column names
    specified in the FOREIGN KEY clause become a foreign key for the
    referencing table.

    When used as the column type clause, specifies that the type
    of the column be inherited from the PRIMARY KEY or UNIQUE index
    referenced. Both the data type and domain are inherited.