Timekeeping

Every date in the Sphere begins with a digit that tells you how much to trust the rest of it.

Overview

There is no simultaneity in the Inner Sphere. Light takes minutes to an hour to cross it, ships take months, and no two worlds share a day or a year. A timestamp is therefore not a fact but a claim, and the Concord's dating system is built around admitting that rather than pretending otherwise.

The format is four fields:

        M3 . 231 . 458 . 4
        │     │     │    └── confidence class: how much to trust the rest
        │     │     └─────── mark: which thousandth of the year
        │     └───────────── year within the millennium
        └─────────────────── millennium

Largest unit first, and the caveat last — which is the whole design. The date makes its claim, then tells you what the claim is worth.

Spoken "em-three, two-thirty-one, four-fifty-eight, at four." Among people on the same world the trailing digit is simply left off: everyone there shares a clock, so there is nothing to qualify.

The confidence class

How well this timestamp is synchronised to the master clock on Terra Prime. It is not a measure of honesty. It is a measure of distance.

Class	Means
0	Set on Terra Prime, against the master clock itself
1	Sol system, continuous laser sync. Drift under a second
2	Inner Sphere, regular broadcast sync. Drift in seconds
3	Routine interplanetary — corrected against the last beacon received
4	Frontier. Last sync days old; drift in minutes
5	Long-haul transit. Reconstructed from ship's clock on arrival
6	Stasis passage. The sleeper's clock means nothing; arrival time inferred
7	Deep Frontier. Last verified sync is months old
8	Reconstructed after the fact, from context
9	Unknown, disputed, or asserted without evidence

A class-7 contract cannot prove when it was signed. That is not a technicality — it is a whole category of dispute, and a great deal of frontier law is argument about which class a document deserves.

The mark

The year divided into 1000 equal parts, each about 8 hours 46 minutes.

It is a decimal accounting year and it was designed by people who bill by the hour. Nobody uses months: a month is Terran, and Terran months mean nothing on Terra-Forge or in the Belt. The mark belongs to no planet, which is exactly why everyone agreed to it.

Three marks is a little over a Terran day — deliberately not a day, because there is no common day to match. A work rotation is usually one mark, so "I'm on till the mark turns" means a shift is ending somewhere, and it is never the same somewhere twice.

Slang

"A nine." Any claim with no verifiable date. "That's a nine and you know it." The single most common way to call someone a liar without saying so
"Same-mark." Effectively simultaneous — close enough that the order cannot be established
"A clean date" or "a zero." Terra-verified, and worth money on a contract
"Marked and marked again" — a document whose date has been reconstructed twice. Worthless

Relationships

Communications — the lightspeed limit the whole system exists to admit
The Feed and the Undernet — where dated claims get repeated and degraded
Terra Prime — home of the master clock

Status

In use everywhere, by everyone, without affection. The confidence digit is the only part anyone argues about.