Apple wants podcasts inside iTunes to put the digital equivalent of a parental advisory on podcasts with foul language or mature topics. While this is very subjective across cultures, it's presumed the benchmark for explicit content is based on the norms in the United States. While the feed for our show made it into the iTunes Podcasts listing without a clear definition this is one designation you may want to include. Apple hasn't made it mandatory for listing yet, but it is most definitely not in their optional tag list.
If you do use explicit content in your show, the tag for your feed looks like this:
<itunes:explicit>yes</itunes:explicit>
A nice wholesome podcast gets no label at all using this tag:
<itunes:explicit>no</itunes:explicit>
