The Cast List is used in Sitcom scripts to indicate which characters are speaking and appearing in the following scene.
Cast Lists are on the line following Scene Headings and look like this:INT. JERRY'S APARTMENT - DAY (JERRY, ELAINE, GEORGE)SPACE - NEAR THE QUADRANGLE BORDER (DR. CONNER, MARCUS, JERRY, ELAINE, GEORGE)
Check the format used for the show you're writing for the exact formatting specifics. The variations you'll see in Cast Lists include whether the list is in order of appearance or importance and, based on the above, whether the list shows speaking characters first, then non-speaking characters.
The Cast List is on the line directly below a Scene Heading, enclosed in parenthesis, with the same margins as the Scene Heading. The specific show will determine if the Cast List should be uppercase or mixed-case and if there's a specific order they want you to use for the characters in the list.
If you have the option to create Cast Lists turned on, Scriptware puts in your Cast List automatically, as you write!