When <tt>command = <i>cmd</i></tt> is set before calling this command, then

<p>
CPU 0 (master) request other CPUs (slaves) to execute <tt><i>cmd</i></tt>,

<p>
Effective only when MD++ is compiled for parallel runs,
e.g. with <tt>SYS = mpicc</tt> or <tt>SYS = mpigpp</tt>.
which can be any MD++ command or variable assignment.
