A term from the supplements "Sex & Sorcery", by Ron Edwards. It is a concept for Social Contract about what the group is comfortable with. cf. also the Interaction Model developed earlier on rec.games.frp.advocacy. The idea is that there is a "line" which marks events that are not allowed in-game, but also a "veil" which marks events which are not described in detail.

For example, a group might decide that rape and mutilation are beyond the line. They don't want such things to happen in-game at all. Thus, rape and mutilation are beyond the line. However, they might decide that torture is acceptable as long as it is not described in detail. Thus, torture is behind the veil. Thus, the veil could be defined as techniques for describing events without providing specific imagery or details.

References:

• Sex & Sorcery
• National "Protect-Your-Players" Day