A scientific approach to a DooM-related problem. And that problem is… Linear/Nonlinear maps: which is which? Wraith777 considered this to be a stupid idea but I really think that this is somewhat enlightening to me - even after 25 years of mapping. Since nobody actually tried to make such a classification and analyze maps based on it he has developed this on his own. And, off course, not everything is 100% definite – those are simply his suggestions based on study and observation of various maps and are subjects of discussion and corrective actions. The shemes and details can be found at the discussion-thread at Doomworld.com.