“…Significant early contributions to the development of the theory of joint seminormality, which prompted us to try and find a unifying framework, are due to Athavale [1], Cho, Curto, Huruya, and Zelazko [7], Curto [11], Curto and Jian [12], Curto, Muhly, and Xia [13], Douglas, Paulsen, and Yan [14], Martin and Salinas [29], McCullough and Paulsen [31], and Xia [44]. The viewpoint emphasized in our article was already outlined in Martin [19,[22][23][24] and is based on some techniques from Clifford analysis and spin geometry.…”