This only applies to people who receive bills from Watercare in New Zealand.  This feature can be turned on and off from the maintenance menu by choosing Options/Features.

The new watercare bills menu option opens up a small window which is designed to quickly create extra charges against tenants.

The window is designed to be used with a barcode scanner.  You can scan the barcode on the water bill, and this will extract the watercare account number.  You then associate that with a property, and also get to select the tenant.  The scanned barcode also contains the total bill amount.  All you then need to do is enter the fixed charge amount (the amount not charged to the tenant) and the variable amount is then created as an extra charge.  When you scan another bill from the same address, the property will already be seleted for you because RentMaster will remember the account number/property association from the last time.