  This paper describes how to use subgroups to parameterize unipotent classes
in the classical algebraic group in characteristic 2. These results can be
viewed as an extension of the Bala-Carter Theorem, and give a convenient way to
compare unipotent classes in a group $G$ with unipotent classes of a subgroup
$X$ where $G$ is exceptional and $X$ is a Levi subgroup of classical type.
