(B)/W
From ACT Wiki
(Better)/Worse
A label and sign convention in financial reporting to indicate whether positive differences are bad news - also known as 'adverse', in other words indicating that the number being compared is 'worse' than the one it's being compared with.
When the label is (B)/W the positive numbers are worse than forecast, budget, prior period or other comparative number.
Under this convention, negative numbers are good news, also known as 'favourable'.
On the other hand, when the label is B/(W) the opposite applies - negative numbers would be worse and adverse.
Under the B/(W) sign convention positive numbers are better and favourable.
