Lineback
A white stripe running along the spine of an otherwise coloured animal.
Also: finching, finched, white topline
A lineback has a white line along its spine, from the withers or the head to the tail, on an otherwise coloured body. In older British usage the marking is called finching. It is a defining mark of the Gloucester, a dark brown breed with a white tail and a white line along the back, and is common in the English Longhorn. In North America the Randall Lineback of Vermont is named for it. Wider stripes shade into the colour-sided pattern. The white line is quite different from the eel stripe, the pale or dark line along the back of the aurochs and of some wild-coloured breeds.