Somebody mentioned "credits" once...I can't remember who.I have my character Ernsto Mons paid in platinum coins. My character Elsa references copper and silver coinage. I'm assuming platinum coins are legal tender but uncommon, copper and silver more common, but I never developed an entire monetary system. In my mind precious metal coins are pretty basic and would be universal just about anywhere, especially in places where mining is a significant activity, as is true in parts of AE. This is not necessarily incompatible with "credits" which could be the equivalent of paper money while a coinage system could exist alongside it. The US once had a system like this, with paper money significantly overlapping in value with precious metal coins, though I don't think we ever had platinum coins.Part of the problem were dealing with here is I don't think anyone has fully defined what the existing political units in AE are and to what degree they are independent from one another. If Zirconia and other underwater environments have full political separation from Avenir and each other, then they each would possibly have their own monetary system. There may be as many as twenty different monetary systems in AE.Precious metal coins may serve as an unofficial bridge between monetary systems, having at least some value everywhere. Though perhaps they could also be illegal in places, perhaps being associated with smuggling.On the other hand, it's possible for separate political entities to share the same money. Togo shares the West African Franc with five other former French colonies if I remember right. The common origin of all the AE settlements could mean they use the same system.I hope this is helpful, even though it raises more questions than it answers. Perhaps you're interested in making something up yourself?
The only story I've done that mentions money was "Panhandler," which was set on Avenir. My panhandler is standing near the food court holding a sign reading, "Alms for Literacy?" and a credit charger. I'd expect that the normal means of exchange would might vary from place to place in the system. I think you're right, Travis, metallic tokens would probably be in almost universal use. The only problem with them is the weight and bulk of carrying them and the fact they're less secure from theft. My thinking is that credit would be used in settled areas such as Avenir or the O-HABs (Oceanic Habitats). Of course, we could always go with currency respected over most of Earth in the 19th century (and in not a few places at present): the gold Sovereign and the Maria Theresa thaler.