  This paper is a contribution to the spectral theory associated with the
differential equation $Ju'+qu=wf$ on the real interval $(a,b)$ when $J$ is a
constant, invertible skew-Hermitian matrix and $q$ and $w$ are matrices whose
entries are distributions of order zero with $q$ Hermitian and $w$
non-negative. Under these hypotheses it may not be possible to uniquely
continue a solution from one point to another, thus blunting the standard tools
of spectral theory. Despite this fact we are able to describe symmetric
restrictions of the maximal relation associated with $Ju'+qu=wf$ and show the
existence of Green's functions for self-adjoint relations even if unique
continuation of solutions fails.
