The Nikon Scan documentation is very good. The online help, which can be started with Help, is rather basic, but there is an extensive reference manual available in PDF format.

The latest versions of the manual can be found on the Nikon support website. Every function is described in the approximately 140-page manual in great detail. The manual also takes advantage of the features of the PDF format: Hyperlinks allow convenient navigation between scan functions. Even without using Nikon Scan, the manual is quite interesting to read to get a general overview of scanning techniques.

The Nikon reference manual is clear, vivid, and informative.