currency-8.x-3.3/config/install/currency.currency.XXX.yml

alternativeSigns: {  }
exchangeRates: {  }
currencyCode: XXX
currencyNumber: '999'
sign: ¤
subunits: 0
label: 'No currency'
usages:
  - { start: '', end: '', countryCode: AQ }
  - { start: '', end: '', countryCode: ZZ }