C ases of registration of marks com prising generic and usual words are very difficult by reason that the examiner shall be extremely prudent as regards limitation of classes of goods, ensuring himself that the consumer will not be misled consequently. Frequently, the use of a trademark in relation to a new product, earlier unknown to the consumer, has the risk to become usual term, if the owner of the trademark does not undertake measures to prevent the consumer from using his trademark by designating other similar goods or goods of the same type, having common qualities and common destination. For example: cellophane, thermos, ruberoid, vaseline, nylon, primus etc.