Specify meaning as well as field names
Document the instrument identifier, quote fields, timestamps, source identity and the representation of missing or invalid data. State the numerical precision and time basis. If a sequence or revision field is available, explain what it can establish and what a consumer must do after a gap.
The protocol, delivery mode and supported requests depend on the selected API. These are proposed contract-review questions, not a claim that TSG supplies a particular undocumented endpoint or transport.
Build a consumer acceptance matrix
| Contract area | Question to settle | Test evidence |
|---|---|---|
| Authentication | How is access scoped, rotated and revoked? | Approved access and denied-access cases |
| Freshness | Which timestamp and expected schedule define current data? | Normal, stale and inactive-market examples |
| Capacity | Which request or subscription boundaries apply? | Agreed consumer load and rejection behaviour |
| Change | How are schema and instrument changes announced? | Version/change example and consumer response |
| Interruption | How does a consumer resynchronise after a gap? | Controlled reconnect and completeness review |
Data licensing and redistribution permissions should be confirmed with the appropriate provider. API connectivity does not itself grant the right to publish a stream externally.
Exercise an incomplete-data condition
Illustrative consumer test: an operational dashboard loses its connection and then reconnects. The team checks whether it can distinguish current data from cached values and whether the interface provides the history or snapshot needed by the agreed workflow.
Hand over an interface specification, a sample payload set and the operating contacts for schema, access and freshness problems. Keep secrets out of client-side website code. Where browser access is required, review the supported security boundary rather than exposing a privileged upstream credential.