What is the current state of the law on jury unanimity and single crime definition?

Recently the United States Supreme Court in Schad v. Arizona, supra, 501 U.S. 624, 111 S.Ct. 2491, 115 L.Ed.2d 555, dealt with the issues of jury unanimity and permissible single crime definition. For purposes of our inquiry the case is significant in that it illustrates clearly the positions various courts have taken on the issues and deals with them at length, albeit with divergent views of their acceptability. Given the significance of the case and the plurality nature of its opinion, we deal with it in depth.