Versioned survey releases
A published geospatial survey release never changes. A correction is issued as a new release that supersedes the last, so a client can always say which version they reviewed, measured and downloaded.
A published release is frozen
A published release cannot be edited, apart from a statutory erasure; a correction is a new release. The only change a published release can ever undergo is being marked as replaced by a newer release, and even then its number, its checksum, its dates and the record of where it came from stay as they were.
What the terms of service say about erasure
The files under a release are frozen with it. What a client downloaded is what was published, and nothing rewrites it in place.
A correction is a new release
Supplementary runs, revised layouts and corrections are all issued the same way: publish again. The new release becomes the current one and the previous release is marked superseded, its record and checksums kept exactly as they were. Its files can still be deleted under the deletion rules.
A worked example
A boundary survey is published on 3 March as release 1 and delivered that afternoon. On 11 March a missed control point is corrected and the survey is published again as release 2. Release 1 is now superseded and is still, byte for byte, the survey the client reviewed on the third — and the receipt from that delivery still names its checksum.
The dates and the survey in this example are illustrative.
Review work sits over the release, not in it
Measurements, notes and conversations sit over the release and never change it. Publishing again is the only act that produces a new version.
What leaves as evidence
- An export carries the release it was taken from and the moment it was taken. Where it contains a computed volume or profile it also carries the notice that it is a planning estimate and not a certified survey document, so a figure cannot be quoted onward without it.
- A delivery receipt names the release and its checksum, which is what ties a downloaded file back to a specific published version months later.
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