Alan in all seriousness, I would think this is something that evolved over time, right? If you look at all the different folks who catalogue new finds they each have their own reference system. All different with some commonalities.
Yep CONECA is and acronym which stands for The Combined Organizations of Numismatic Error Collectors of America. those are simply their catalog numbers of all the errors they discover and track. I think, IIRC, Wexler at one time decided to leave the error game and sold his long running catalog to CONECA. But then he got back into error attributing and has begun his own catalog again.
The Variety Business has become entirely too populated over the years, despite the good intentions of everyone working in the field. There are issues for which you would want to reference your coin in as many as half a dozen different relevant numbering systems. And then there are places like Cuds On Coins which don't really define themselves within the limits of any numbering system, only obfuscating things further. Makes you wish the ANA would pass a resolution defining specific variety identifying systems, or something. There's no excuse for information to be so all over the map in the Age of the Internet.
DDO,RPM, etc. were used decades ago as abbreviations. Unfortunately, I cannot say who first put #'s to them. That should be easy to discover with a search in the ANA library. Second thought...Real Librarians (Degree in Library Science) love a challenge. Perhaps, one of the women at the ANA would like to answer this for us.
This reference system was first published by Kevin Flynn. The numbering system was subsequently referenced by CONECA and Snow, who sometimes called them 'Flynn' numbers. Insider's suggestion is excellent. I'm a couple of years ahead of you.
