The pattern depth in courses is dependent upon the number of feeds with selection facilities and whether the selection can be changed during knitting.
This sentence has been recited from Knitting Technology by David J Spencer. If the above sentence was written in the following way, it could make sense to me.
........whether the selection can be changed during knitting or not.
I don't know when only whether is used, and when whether is used with or not. When only whether is used, please say, what does it mean?