How do map corrections work?

[glen_s]

I am just curious, where I live almost all of the rural highways seem to be anywhere from 10 to 100 meters off for long stretches, and the town I live in shows me one street over from the one I am actually on, so the unit is virtually useless for finding an address in the town.

Is the map corrections supposed to record data to fix these types of errors?, or is it just for misnamed streets, direction of travel etc..

Is there a way for the unit to plot out whole roads so that they can be corrected, or in the case that the road does not exist on the map, created?

thanks!