  A necessary and sufficient condition for a central simple algebra with
involution over a field of characteristic two to be decomposable as a tensor
product of quaternion algebras with involution, in terms of its Frobenius
subalgebras, is given. It is also proved that a bilinear Pfister form, recently
introduced by A. Dolphin, can classify totally decomposable central simple
algebras of orthogonal type.
