Final answer:
Referential integrity constraints in databases can specify actions such as CASCADE, SET NULL, and update propagation.
Step-by-step explanation:
In the context of database management systems, referential integrity constraints are rules that enforce the relationships between tables. One of the actions that can be specified in referential integrity constraints is the ON DELETE CASCADE action. This means that if a row in the referenced table is deleted, all dependent rows in the referencing table will also be deleted.
Another action is the ON DELETE SET NULL action. This sets the foreign key value in the referencing table to NULL when the referenced row is deleted.
There is also the ON UPDATE CASCADE action, which propagates updates from the referenced table to the referencing table. If a value in the referenced table is updated, all dependent rows in the referencing table will be updated as well.