Grinding machines and grinding tools for grinding machines; grinding apparatus in the nature of machines and grinding tools for grinding apparatus; grinding wheels for use in machines, in particular worm grinding wheels, grinding rings, dish grinding wheels, profile grinding wheels, single profile grinding wheels, rough grinding wheels, disc grinding wheels; grinding wheels for power tools; cut-off wheels for use in machines; flex grinding wheels for use in machines; package of grinding wheels for use in machines; vulcanized fibre discs for use in machines; grindstones for use in machines; grinding bits for use in machines; grinding inserts for machines; abrasive belts for hand-held machines; grinding instruments for machines