  We establish continuity of the integral representation
$y(t)=x(t)+\int_0^th(y(s)) ds$, $t\ge0$, mapping a function $x$ into a function
$y$ when the underlying function space $D$ is endowed with the Skorohod $M_1$
topology. We apply this integral representation with the continuous mapping
theorem to establish heavy-traffic stochastic-process limits for many-server
queueing models when the limit process has jumps unmatched in the converging
processes as can occur with bursty arrival processes or service interruptions.
The proof of $M_1$-continuity is based on a new characterization of the $M_1$
convergence, in which the time portions of the parametric representations are
absolutely continuous with respect to Lebesgue measure, and the derivatives are
uniformly bounded and converge in $L_1$.
