'U' films may contain references only (to 'making love' etc.)
'PG' films may only contain mild sex references and innuendo.
'12' films should not go beyond what is suitable for young teenagers. Frequent crude references are unlikely to be acceptable.
'15' films may have strong verbal references but the strongest references are unlikely to be acceptable unless the context justifies it.
'18' films are allowed to make most references to sex but nothing encouraging an interest in sexually abusive activity.
