In which scenarios should the Magento module pass the `BankID` parameter to AlphaCommerceHub?

The BankID request parameter is marked as optional in the «API Integration Guide(Nov 2017)» → «API Reference», so I do not understand when the Magento module should or should not pass it to AlphaCommerceHub:

Parameter Name Type Format Mandatory Description
BankID Alpha O The ID for the bank sponsoring the merchant

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