It is demonstrated, first by a specific example related to Einstein's "train" and then by a more general argument, that absolute synchronicity of clocks permanently at rest is various inertial systems is attainable without any transport of the clocks or use of light signals, provided that a method is agreed upon for synchronizing clocks in a single inertial system. The assumption on which this rests is that relative clock rates are determined by their relative states of motion, not by their locations in space (either absolute or relative to an observer or coordinate origin). It is then shown that the same result, absoluteness of simultaneity, together with related results such an length invariance, can be attained by use of light signals, compatibly with a relativity principle, provided these signals are described by neo-Hertzian, rathen than by Maxwellian, electromagnetism.
