Milestone

A Milestone is a point — or an interval — in a Transaction’s lifecycle: instruction, offer accepted, exchange, completion, registration, and the processes between them.

Why it matters

Milestones are how a Transaction’s progress is observable. They carry timestamps (planned and actual), associated parties, and a variance gap that tells you whether a transaction is on track. Some Milestones are instants (offer accepted at 14:32 on this date); others are intervals (completion-process started at X, ended at Y). OPDA distinguishes both — instants and intervals — so consumers can ask “when did this happen?” and “how long did it take?” with the right answer in each case.

If you are running a transaction-management platform or feeding a regulator dashboard with on-time performance metrics, these are the entities you read.

Hard cases

• Instant vs interval Milestone. Offer-acceptance is an instant (one timestamp); the completion-process is an interval (start + end). The model captures both shapes — naive timestamp-only modelling discards the interval data.
• Planned vs actual variance. Every Milestone has both a planned timestamp (on a companion Plan) and an actual timestamp (on the Activity). The variance feeds regulator-grade on-time performance reports.
• Re-planned Milestone. A delayed exchange triggers a re-planning. The planned timestamp updates; the actual timestamp does not exist yet. The variance is computed against the current plan.

Identity Criterion

A Milestone is identified by its (Transaction, Milestone-kind, occurrence) triple — the Transaction it belongs to, the kind of Milestone (instruction, offer accepted, exchange, completion, registration, etc.), and the occurrence index if the Milestone can recur. See the Logical tier → for the typed structure (instant vs interval distinction, planned/actual timestamps, variance derivation).

Related Kinds

• Transaction — Milestones belong to a Transaction

Related-Kinds graph

Source ODR

ODR-0007 — Transactions and lifecycle §Q2