PART VI - WHEN THE CALENDARS HAVE TO TALK
Operating in an Inhabited Solar System

So far, this book has mostly looked at calendars one world at a time.

That was necessary to establish the architecture. Mars showed one local implementation. Jupiter and Saturn showed planetary systems. The asteroid belt tested a population. Pluto found a boundary. Venus and Mercury showed that the two calendars can separate completely.

But a mature Solar-System civilisation will not consist of isolated calendar islands.

People will move. Organisations will operate across worlds. Contracts, records, logistics, communications and software will cross astronomical environments whose days, months and years mean very different physical things.

That is the final test.

Part VI follows five steps from local calendar to shared civilisation:

MOVE — what does a person actually have to relearn when changing worlds?

ORDER — how can many local calendars still describe one shared history?

CONNECT — what additional intuition appears once their orbital calendars share a common orientation?

LIMIT — which problems should Solarian deliberately refuse to solve?

BELONG — after all the machinery is stripped away, what genuinely needs to remain common?

The movement is from the traveller to the civilisation.

Solarian does not try to make every world share one calendar.

It tries to make different calendars understandable to one another without stripping away the local identity that made them worth having.

That is what interoperability means here:

different worlds, local time, one intelligible grammar.