How to read carrier record history

Source history can predate Baseline

FMCSA publishes authority history. An event in that source may carry a date earlier than Baseline’s retrieval. It should be described as a source event, not as a change Baseline witnessed on that date.

Observed change requires retained observations

To say a phone changed from one value to another, you need two retained observations of that field. A current phone alone cannot establish the previous value or when it changed. The first time a new value is seen is not necessarily its effective date.

Keep three timestamps visible

An intelligible timeline separates the source event date, the retrieval timestamp and the first-observed timestamp for a comparison. When one is unknown, leave it unknown. Do not substitute the page publication date.

A failed refresh is an open question

If a later source request fails, the earlier value remains an earlier value. It is not confirmation of no change. Review the last successful retrieval time and return to the source before drawing a freshness-dependent conclusion.

Baseline’s paid observation timeline is planned. Public source-dated authority events, where held, remain distinct from that future workspace history.