7.87.Article 39 makes it an offence for a person (A) intentionally to control any of the activities of a child (B) that relate to the child's prostitution or involvement in pornography in any part of the world. The offence is committed even if B's activities in relation to prostitution or pornography are controlled for part of the time by another person. An example of the behaviour that might be caught by this offence is where A requires or directs B to charge a certain price or to use a particular hotel for her sexual services or to pose for a certain photographer and B complies with this request or direction. The prostitution or pornography can take place in any part of the world. Where B is 13 or over, the offence will not be committed where A reasonably believes that B is 18 or over. (It will be for the prosecution to prove that A does not reasonably believe that B is 18 or over.) However, where B is under 13, A will commit the offence regardless of any belief he may have about B's age. The terms "pornography" and "prostitution" are defined in Article 41.