I figured that TravelBuzz is about the most appropriate place for this post (not that any of the fora are particularly right for this question), but here goes.

A lot of airline's paint schemes feature a thin line that runs along the plane horizontally (near the window or above or below it). I think I'm describing it correctly. This is often referred to as a "cheat line." Does anybody know the origin of the term "cheat line." I understnad the "line" part of it by why the "cheat" part.

Thanks for any info.