Field help (ISRREFNUM) 

This field displays the ISR reference number created for an invoice if the SWICUSBVR - Swiss ISR usage Sales (LOC chapter, SWI group) parameter is set to Yes. If a new invoice is created, the ISR reference number is calculated when the invoice is saved.

When the SWICUSBVR parameter is set to Yes, this field only displays a value if an ISR payment term is used and the invoice currency is CHF.

If you copy an invoice, the existing ISR number is removed. A new number is created when the copied invoice is saved.

Refer to the Swiss legislation guide available from the How to tab of the Online Help Center for a global view of how to use the ISR.