The Tartan Puzzle is a Latin Puzzle inspired by the tartan fabric, “...a pattern consisting of criss-crossed horizontal and vertical bands in multiple colours. Tartan is particularly associated with Scotland: scottish kilts almost always feature tartan patterns.” (wikipedia).
In a Tartan puzzle two rows or two columns with the same letter make up a pair. Each pair of rows, eacg pair of columns and each 4x4 sub-square must contain all numbers 1 to 16.