<Dd> Under 17 requires accompanying parent or adult guardian . Contains some adult material . Parents are urged to learn more about the film before taking their young children with them . </Dd> <Tr> <Td> </Td> <Td> <Dl> <Dt> NC - 17--Adults Only </Dt> <Dd> No One 17 and Under Admitted . Clearly adult . Children are not admitted . </Dd> </Dl> </Td> </Tr> <Dl> <Dt> NC - 17--Adults Only </Dt> <Dd> No One 17 and Under Admitted . Clearly adult . Children are not admitted . </Dd> </Dl> <Dt> NC - 17--Adults Only </Dt>

The u.s. movie rating system is an example of