Correction to ``Two-groups on finite translation planes'' (Q1093890)

Let \(\pi\) be a translation plane of order \(q^ d\), with kernel GF(q). The paper being corrected [Arch. Math. 47, 568-572 (1986; Zbl 0588.51003)] was an attempt to improve on earlier results to the effect that if the translation complement contains an elementary Abelian group of order \(2^ c\), then \(2^{c-2}\) divides d. Our proof was based on some tacit unjustified assumptions and hence is incorrect. The following now appears to be a fundamental question for the theory of finite translation planes: ``Is there a translation plane of order \(q^ 4\), where q is prime to two and three such that the translation complement contains a quaternion group of order q whose fixed point subspace is a subplane of order q?''