The root Lems element. jLEMS only optional attribute to also write a short report with simulation duration, version, etc. jLEMS only optional attribute to also write a file containing actual times used in the simulation. Some have asked whether fractional dimensions should be allowed. Disallowing it until needed... A value for a physical quantity in LEMS, e.g. 20, -60.0mV, .05 per_ms or 5nA