In heraldry, the baton is an ordinary in the shape of a thin diagonal line starting in the dexter chief, but not reaching the edges of the shield. It is a diminutive of the bend. If the baton starts in the sinister chief it is called a baton sinister.
By the 17th century this a baton sinister was also used to indicate illegitimacy. This usage is also mentioned as being used in Burgundy in 1463.