On days when outings follow one another — several teams, passengers to settle in, dogs to look after between two loops —, nobody sets anything up at the start. The GPS counts everything: the time spent hooking up, the wait after the finish, sometimes a distance thrown off by a stop in the wrong place. It is in the evening, at the computer, that you go back over the day.
What changes
On the page of an outing recorded by GPS (or imported from a GPX file), the owner and the handler find "Correct the measurements", under the "Musher" line. Three fields: the distance, the moving time, the elevation gain. You only touch what is wrong; whatever you leave as it is does not move.
The average speed recomputes itself. The load of the outing's dogs is recomputed with the declared figures, and they are what the statistics, each dog's kilometres and the leaderboards count.
The page then says so: "Declared figures — measured by GPS: 12.40 km · 1:00:00 · D+ 150 m". Every member of the kennel sees this line, and the banner at the top shows the declared figures.
What others see, and what they don't
A published outing keeps its public link, with its declared figures; the public page does not say they were declared, and never shows the GPS measurement. Nobody sees who corrected it or when: the database keeps it, the screen does not show it.
What the correction does not do
It does not cut the track. The map, the speed chart, the splits, the team layout and the stops remain the GPS ones: if the start included ten minutes of hooking up, the map still shows them. The correction is about the outing's figures, not its drawing.
It does not apply to outings logged by hand — their figures are already corrected under "Correct" —, nor to Strava imports, which keep Strava's figures, nor to races, whose official time is declared elsewhere.
The phone receives the declared figures with the outing, but does not show the "Declared figures" mention, and an outing already sent is not corrected there.
The choices that are not obvious
The GPS measurement is kept, not overwritten. A figure typed in the evening can be wrong in turn; keeping the original measurement lets you come back to it, and the mention tells the whole team that the figure shown was declared.
Correcting twice loses nothing. It is always the very first measurement that stays alongside, not the previous correction.
An emptied field erases nothing. Correcting means declaring another figure, never erasing a measurement: a field left empty keeps the current value.
The small stop correction disappears when you declare the distance or the time, and the hook-up time when you declare the time. They described the GPS measurement; applied to a figure typed by hand, they would skew it.