Machine-readable coded data disposed on or in a substrate in accordance with a layout, and method of generating such coded data The layout has at least order n rotational symmetry, where n is at least two, and includes n identical sub-layouts rotated 1/n revolutions apart about a center of rotational symmetry of the layout. The coded data is disposed in accordance with each sub-layout including rotation-indicating data that distinguishes the rotation of that sub-layout from the rotation of at least one other sub-layout within the layout.