It is still confusing. No different to TT.
*A = Star Alliance and makes perfect sense
*O <> Oneworld and makes no sense. Even OW make no sense for extremely obvious reasons
CD <> chauffer drive and is a totally stupid abbreviation
I'm sure at some point abbreviations don't make a lot of sense until you get it. Naturally, you don't have to use it
As I mentioned, *O is the CRS code for
oneworld, so forum people didn't just make it up, and certainly didn't just make it up to specifically annoy you!

Oddly enough, it is contained in the AFF
http://www.australianfrequentflyer....ions/abbreviations-and-explanations-5056.html. For example, the following Amadeus command will summon a list of
oneworld flights between Hong Kong and Tokyo Narita:
AN*O19JANHKGNRT
My only guess as to why *O was used as the CRS code is because in a CRS, given it is an alliance and not an airline, a generic code was used to denote this, and one way to try and differentiate it as such is to use a symbol, and * is a fairly common symbol in computer parlance to denote a wildcard. Now that's me guessing!
For what it is worth, *A is the CRS code for Star Alliance and *S is the CRS code for Skyteam.
I prefer to use
ow myself for
oneworld, i.e. the
o is specifically bolded (or inversed to the boldface in use). I can see OW being confused with possibly "one way", though context should give it away; sometimes for "one way" I use o/w (but that can also be 'confused' with "otherwise"). The last airline to use OW as its IATA code is now defunct.
CD wouldn't be obvious to me as "chauffeur drive" if it were on its own.
I don't use TT for "Trans-Tasman" as it could be confused with the code for Tigerair. Whilst in some cases it's clear from context (e.g. TT don't operate any flights to New Zealand), I still don't like it, and in other contexts it is ambiguous (e.g. "How many TT flights have you done this month?")
Sometimes a bit of context helps a lot.