I cannot find Scott 1305Ev (Holmes coil, Type I, dull gum) in my Scott 2011 Specialized. There is a listing for the dull gum variety under 1305E, but is not designated as "v".
I assume catalog # 1305Ev exists because stamps are listed as this number in several online sales. Also, I have this number in a database of US stamps that I created some time ago, but I don't know how I knew to include it when I created the database.

Since Scott is the entity that assigns catalog numbers to stamps, (at least I think Scott does), how did 1305Ev get numbered but not end up listed as such in the catalog?