A marker including a support with a front surface and a back surface, a light generating element fixed on the back surface of the support, and a device for fixation of the light generating element on the back surface, wherein the support includes at least three openings placed at predetermined positions on the support, wherein the light generating element is fixed on the back surface of the support by the device for fixation to cover the openings such that the light generating element is detectable through the openings by the tracking system, and wherein the light generating element can be placed or removed or replaced during an operation with the device for fixation.
