If you set an LVar in XML code:
(E:ABSOLUTE TIME, SECONDS) (L:XIP_ABSOLUTETIMESTART) - (>L:DA40180XIP_ABSOLUTETIME)
var currenttime = SimVar.GetSimVarValue("L:XIP_ABSOLUTETIME", "seconds");
A number around 63000000000.000 give or take. How ever if you now save that number back
SimVar.SetSimVarValue("L:XIP_ELAPSETIMESTART", "seconds", currenttime);
it will not save correctly you get a number that is close but not the same.