The concept of Apple Computer’s Hypercard program is so unfamiliar to the average computer user that the company itself has trouble describing it – but that has not hindered the thing from shaping up as a runaway success: the Wall Street Journal reports that a $30 title, The Complete Hypercard Handbook, has already sold 100,000 copies and that Hypercard stacks collections of linked screens of data – are being created in hundreds and mail-order software firm Heizer Software says it is getting two or three new stacks submitted a day, and will be listing 100 in its next catalogue.