Welcome to the world of cinderellas. Until the late 1950's, there was no accepted terminology for this area of stamp collecting. Then a group in Great Britain began the Cinderella Stamp Society and named the area for posterity. As in the fairy tale, these are the stepchildren of stamp collecting. They reside on the fringes of philately.often regarded as trash, but some are treasures awaiting discovery.
Information is the key.
This is truly a treasure hunt. The prize is knowledge and interesting stories. It demands more of a collector than the crossing off of want lists and the filling of album spaces. This is a treasure hunt without much of a map. If you're up to it, it could be the opening to a whole new world of collecting and fun.