“Lines and Veils” are a safety tool designed to be first employed in a session zero and revisited as needed throughout a campaign. When discussing the tones and goals for the game, the GM (or another player) should make a list of everyone’s lines and veils. Lines are topics that players do not want in the game. They should not appear in any form. Veils are topics that players do not want to feature in the game, but can still exist in the world. Treat lines and veils like a living document—the list can be updated by anyone at any point.