Sales Order Returns Reference field name

Good day!

I would like to ask what is the field name for the Reference column under the Returns tab for the Sales Orders. I have a requirement where in sales returns should not be able to automatically deduct form the original invoice, hence, the Reference field should be left blank to achieve this. I am planning in creating a personalization to automatically make the Reference value to blank so that the end users do not need to remove it as some may forget to change it. I hope I have explained this properly.

Best regards,

Victor

Edit 1: Additionally, I learned that you can also just delete the Credit Invoice field value from the same Returns tabs instead of the Reference column as discussed here.