Using the [Kriging tool in ArcMap][1] I'm a bit confused on the meaning of parameters.

The interface asks for lag size, and optionally range, partial sill and nugget.

My understanding is that lag size is only relevant for binning samples to estimate the values of range, partial sill and nugget in the semivariogram model; in this case lag specifies the size of the bins (though this itself is not clearly documented in the link above - could it also refer to the distance of the furthest bin?).

I presume if I don't provide the other parameters, then the Kriging tool will calculate them based on my lag size.

But if I do provide the other parameters, 

1. what is lag size (which is compulsory to provide - a default is calculated from cell size if you don't) being used for?

2. does it refer to the bin size, or the distance of the furthest lag?

  [1]: https://desktop.arcgis.com/en/arcmap/latest/tools/spatial-analyst-toolbox/kriging.htm