A balance is the calculated amount of money associated with a bank account. Banking systems may provide multiple balances because calculation methods differ, but exposing every option can burden consumers with choosing among them. section 8.4.1
Choose a single, commonly used balance when users are non-experts or use cases do not distinguish balance types. Retain multiple balances when those distinctions matter, especially for expert consumers. section 8.4.1
A self-interpreting balance model
A balance amount should identify its currency rather than expose an unexplained number such as 123. When several balances are needed, represent them as a balances array, for example objects typed "value-date" or "expected", with a Boolean default flag on the commonly used balance. section 8.4.2 section 8.6.2
Figure 8.15 Different properties representing the same type of data may be grouped into an array.
Use the array structure to make multiple balance types explicit and easier to browse in code or a JSON viewer. section 8.6.2
