It is not Admin who gave the sets that are NNO numbers. Every time I come accross a set here in the database that has numbers asssigned when they should be NNO, I report it through the inaccuracies function and it gets corrected by Admin. I believe it is either copied from other sources (as said before) or some members who input the checklists with numbers when they should be NNO. I prefer the accuracy we are trying to achieve here so that when I am looking to find a specific card, I can use NNO in my search if that is all I have.
The only variation to this accuracy in listing cards that I do like is one source I use (I am one who hates Beckett for what they did to the hobby) is a use of brackets around the number in the checklist when the cards are NNO, e.g. (26). What this allows is when putting cards of an incomplete set in plastic sheets, a collector can place the card in the right pocket and not have to move it every time a new card is found (this assumes that a collector puts a set in alphabetical order when the cards are NNO).
Bruno
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Check my Profile page to see my 2023 Goals and my Lists of sets near completion (5 cards or less) or sets getting close (less than 100 cards missing and 75% complete).
https://www.tcdb.com/Forum.cfm/Page/B/ID/0/?MODE=VIEW&ThreadID=25745&C=0