a purchaser of a block of shares in a co-operative corporation which is the beneficial owner of a recreational vehicle park thereby becomes entitled to be licensed a particular site in the park provided that the purchaser pays his or her portion of the "assessments" for common costs. Such purchase, which is characterized as a single supply of real property by way of license, is not exempt under s. 7(a)(i) of Part I of Sched. V given that, except in exceptional circumstances, a recreational vehicle does not qualify as a residential unit. The payment of the assessments also is not exempt under s. 7(a)(i).