I am convinced it is because the RF section of the Specialized frankly sucks.
Eric, or any one else who has influence with the catalog, please get them to redo in a manner that actually IDs the stamps. Personally, I think a grid with overprint scans would do the trick.
It would really help if there were words to the effect that your really rare playing card overprint is always trumped by the 90 cent "8 Cts."
As Ron can attest, I too fell for overpaying for what I thought was one of the scarcer cat numbers. I simply didn't know enough about RFs and looking it up in the specialized didn't help. In my opinion, the note after RF7 simply isn't clear enough
Now I collect RF16 by company canx

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Here is the one that taught me my lesson:
