They show the field boundaries.

NPR: Crop Cops Take to the Sky

House and Price show how HP blurred boundaries in useful ways.

FORBES: Magazine Article

In the first two seasons of the show, Nucky (played by Steve Buscemi) had sought to keep boundaries between his career as an elected official, his business as a bootlegger, and his personal life.

FORBES: Nucky Thompson: Know Yourself Before You Can Get What You Want

For the children, the show is a new experience: a humorous, high-energy piece of foolish theatre that transcends the boundaries of culture, language, age and race.

ECONOMIST: On the road with six clowns in Israel and Palestine