Viring is using one budget to pay costs in another.
For example, a budget-holder may be allowed to use an underspend on advertising to cover an overspend on stationery.
An advantage of allowing viring between budgets is that budget-holders have more independence to make their own decisions, as long as they hit their overall target.
A disadvantage of allowing viring is that budget-holders, if able to set overspends against underspends, can fail to take overspends seriously enough.
