Your idea of expressing time in user-speicifed units from a given origin
sounds useful and analogous to the UDUNITS package. I agree with the
advantages you state. However, this method still has the problem of
insufficient precision for long spans with small ticks, as has been
expressed by others recently. It would seem important to allow
nested origins or multiple origins to accommodate long time spans.
For example,
time:units = "days @ (1850-2-11 12:53:45 -700)";
subtime:units = "microseconds @ (time)";
subsubtime:units = "attoseconds @ (subtime)";
The syntax is imprecise, but this might be a solution.
Fred