Responding to calls for pre-watershed TV shows to feature warnings to stop children from viewing inappropriate material, regulator Ofcom said it has issued new guidance that says unsuitable material that should not generally be shown before 9pm.
It includes "everything from sexual content to violence, graphic or distressing imagery and swearing," the regulator said.
An Ofcom spokesman said:
The protection of under 18s from inappropriate material is a fundamental concern for Ofcom. There are clear broadcasting rules designed to protect children, which we actively enforce.
We recently issued new guidance on the TV watershed, warning broadcasters to be more careful about programmes they show before 9pm that could be unsuitable for children.
We constantly monitor audience attitudes and our research shows that the vast majority of adults believe the current level of TV regulation is about right.
TV programmes should carry warnings at the start to stop children being exposed to inappropriate, violent or explicit material, headteachers have said.
More action needs to be taken to make sure that shows screened before the 9pm watershed are suitable for the audience and to prevent youngsters from witnessing adult themes, according to the National Association of Head Teachers.
Amanda Hulme, head of Claypool Primary School in Bolton, who is proposing a motion on the charter at the NAHT's conference in Birmingham, said: "In the last couple of months there has been examples of inappropriate language before the watershed."
In one case, someone used the phrase "bloody hell" and in another "p**s off" was used, she claimed.
"I think that's completely inappropriate," she added. "If I used either of those phrases in school, either in assembly or in front of a group of children there would be serious repercussions."