Surgical apparatus and instruments; medical apparatus and instruments other than for dental purposes; apparatus and installations for the production of X-rays, for medical purposes; medical x-ray apparatus; apparatus for use in medical analysis; measuring instruments for medical purposes; medical instruments for brain surgery; collimating position indicating apparatus for medical use; skin markers for surgical use; medical diagnostic apparatus and instruments; diagnostic imaging apparatus for medical use; diagnostic measuring apparatus for medical use; medical apparatus and instruments in the fields of clinical diagnosis; electrodes for medical use; surgical robots; medical apparatus and instruments; surgical apparatus and instruments for medical use; shape measurement apparatus for medical purposes; optical tracking apparatus for medical purpose; recognition markers for medical purpose, namely, tracking sensor; medical stereotaxic apparatus for surgery; medical apparatus for accurate treatment positioning for patient in the field of neurosurgery; medical instruments for use in neurosurgery, brain surgery and spinal surgery; surgical instruments for use in neurosurgery, brain surgery and spinal surgery; medical apparatus for use in neurosurgery, brain surgery and spinal surgery; medical apparatus and instruments for displaying surgical images; medical imaging apparatus for surgical procedures; surgical navigation system apparatus consisting of sensors or markers that provide information about the anatomy of a tracker/patient; surgical robot (consisting of surgical instrument/cannula/medical navigation probe/medical navigation camera/medical navigation camera stand/surgical robot arm stand); medical apparatus for creating and providing surgical navigation information (other than for dental purposes); medical imaging apparatus for surgery (accessory of imaging/navigation); medical navigation apparatus for surgery (accessory of imaging/navigation); medical instruments for stereotactic surgery; image guidance systems for stereotactic surgery; compact medical and surgical instruments for use in combination with a traceable surgical navigation system (other than for dental purposes)