Hi Bas - the ‘domain’ of a curve or surface, that is the range or size of it’s ‘parameter space’ can be any two (increasing) numbers - Re[arameterize lets you set those numbers and the Automatic option sets the numbers to something close to

0>3d size of the object.

For example, draw a new control point curve with a few points - measure its length and also its domain (`Domain`

command). Then move points around to make the curve noticeably longer or shorter - the length will not longer match the parameter space domain of the curve which remains as it was when you created the curve…

`Reparameterize > Automatic`

will reset that to match the length. Similar for surfaces though there of course its an approximation unless the thing is a simple rectangular plane since size is not constant.

-Pascal