The field equations of supersymmetric Yang-Mills theory in,ten dimensions m
ay be formulated as vanishing curvature conditions on light-like rays in su
perspace. In this article, we investigate the physical content of the modif
ied SO(7) covariant superspace constraints put forward earlier [11]. To thi
s end, group-algebraic methods are developed which allow to derive the set
of physical fields and their equations of motion from the superfield expans
ion of the supercurl, systematically.
A set of integrable superspace constraints is identified which drastically
reduces the field content of the unconstrained superfield but leaves the sp
ectrum including the original Yang-Mills vector field completely off-shell.
A weaker set of constraints gives rise to additional fields obeying first
order differential equations. Geometrically, the SO(7) covariant superspace
constraints descend from a truncation of Witten's original linear system t
o particular one-parameter families of light-like rays.