Yes, each currency have specific "currency code" that is used in banking system. One country could have multiple "currency codes" for publicly only and single country currency. Same currency, say, "US dollar" or "Russian rouble" could have different properties (including, f.e. does it backed with gold or not) when used inside banking system with different "currency codes". When you withdraw money from banking system it is only one, public "currency code". You can't withdraw money with non-public "currency codes", but banks, stocks and other elite entities could easily operate in that non-public code.
F.e. I found not only regular "US dollar" with 840 code, but also some other "US dollars" with codes 997 and 998. May be there exist another "US dollars", including that lawful money "US dollar". Intersting what they are, how they differ from 840 USD, what their specific properties and could you withdraw or exchange your regular "US dollars" to that another "US dollars".
As I understand, you have FOIA and could demand an answer to that tricky questions, interesting if anybody tried to request info about currency codes used in US banking system with description and reasons for existence.
Is this the most you refer to? https://www.six-group.com/dam/download/financial-information/data-center/iso-currrency/lists/list_one.xml
Yes, each currency have specific "currency code" that is used in banking system. One country could have multiple "currency codes" for publicly only and single country currency. Same currency, say, "US dollar" or "Russian rouble" could have different properties (including, f.e. does it backed with gold or not) when used inside banking system with different "currency codes". When you withdraw money from banking system it is only one, public "currency code". You can't withdraw money with non-public "currency codes", but banks, stocks and other elite entities could easily operate in that non-public code.
F.e. I found not only regular "US dollar" with 840 code, but also some other "US dollars" with codes 997 and 998. May be there exist another "US dollars", including that lawful money "US dollar". Intersting what they are, how they differ from 840 USD, what their specific properties and could you withdraw or exchange your regular "US dollars" to that another "US dollars".
As I understand, you have FOIA and could demand an answer to that tricky questions, interesting if anybody tried to request info about currency codes used in US banking system with description and reasons for existence.