Demurrage and detention are two clocks.

Two clocks, two counterparties, one board — and an audit of the carrier’s own invoice.

2
Clocks per container
Two start events, two counterparties. One field cannot hold both.
What it does

Every row names the clock, and who is owed.

Fig. 1 — Two clocks, not one column.Illustrative workflow
Discharged Last free day Out the gate Returned Demurrage — the box is in the terminal Charged by the terminal. Stops the moment it is released. Detention Charged by the carrier, until the box comes back.
They answer to two different companies; merge them and the dispute gets argued with the wrong one.
Proof

The invoice is checked, not trusted.

Twenty items, checked automatically

Every carrier invoice is checked against all twenty items §541.6 requires, clause by clause.

Thirteen days late, caught at once

§541.7 allows thirty days to invoice; one on file arrived forty-three days after the charge.

Get a demo

A D&D invoice, audited live.

Run against §541.6 during the call, with a dispute letter ready if it fails.