X-ray films, exposed; X-ray laminographic inspection apparatus, other than for medical use; X-ray photographs, other than for medical purposes; X-ray plates (exposed) other than for medical use; X-ray producing apparatus (other than for medical use); X-ray scanners (other than for medical use); X-ray sensitive films (other than for medical use); X-ray spectroscopy apparatus (other than for medical use); X-ray structure analysis apparatus (other than for medical use); X-ray structure analysis instruments (other than for medical use); X-ray tubes not for medical purposes; X-ray viewers other than for medical use; Xerographic copying machines; Yarn detectors for signalling the absence of yarns; Yarn detectors for signalling the presence of yarns; Zener components; Zener diodes