quiggles said:
My understanding is that the Chinese currency is the yuan renminbi. And yes, they are interchangeable.
Chinese currency in general is referred to as "renminbi" (the people's money), while "yuan" is a specific unit of that currency (the equivalent of our dollar, although with only about a fifth the value). One tenth of a yuan is a jiao (10c) while a 100th of a yuan is a fen (cent). These days I don't think you'll find anything that's not a multiple of one jiao - at least not in the cities.
To make it more confusing, when speaking prices the words "kuai" and "mao" are used instead of yuan and jiao. So "shi kuai ba mao" is Y10.80. Back when fen were still used, "shi kuai ba mao liu" would be Y10.86 - the word "fen" wasn't normally added to the end.
Regarding the two currencies, a few decades ago they had foreign exchange certificates as well as the local renminbi, but the FECs were dropped back in the late '80s. Only FECs could be changed back to foreign currency, and whenever you spent them, you'd inevitably be given local renminbi as change. The locals liked to collect the FECs as well (although I don't know what they did with them when the currency was dropped).
I've attached a few things from 1982 when I was there: a 10 yuan FEC, the back side of a 5 yuan FEC, a one jiao note, a one fen note (a rarity even back then), a couple of food vouchers, and the coins in use then - one, two, and five fen (all little aluminium discs).
Cheers,
GP