  The ILC Technical Design Report documents the design of a 500 GeV linear
collider, but does not specify the center-of-mass energy steps of operation for
the collider. The ILC Parameters Joint Working Group has studied possible
running scenarios, including a realistic estimate of the real time accumulation
of integrated luminosity based on ramp-up and upgrade processes, and considered
the evolution of the physics outcomes. These physics goals include Higgs
precision measurements, top quark measurements and searches for new physics. We
present an "optimized" operating scenario and the anticipated evolution of the
precision of the ILC measurements.
