Spinor norm for skew-hermitian forms over quaternion algebras

We complete all local spinor norm computations for quaternionic skew-hermitian forms over the field Q of rational numbers. This can be used to compute the number of classes in a genus of skew-hermitian lattices of rank 2 or larger over a maximal order in a quaternion algebra D over Q in many cases, e.g., when D ramifies at infinity. Examples are provided.