idvalue is sourced directly from the bank. It is a unique identifier created by the bank to reference the customers' accounts within their own systems. It does not (and should not) contain any identifiable bank account information such as sort-code or account number.
If you wish to see this for yourself - Make a call from postman with the raw=true parameter
For example, you can see below that RBS has a unique reference account for an account beginning with 47D4E5…… You see this as
IDin the response from our API but as
AccountIDin the response received from RBS (the raw data)
Yapily API response payload extract showing
The 'raw-data' from the bank used to generate Yapily's API response showing "AccountId=47D4E5……"