I have never seen this particular formula either but I have seen something similar being used frequently.
Hedge costs are computed as $$(Fwd\ Pts/Spot)/100 $$
and annualized (usually with exact days though, like ACT/360 or ACT/365).
fwd pts = 50
spot = 110
days = 91 (for 3m and daycount subject to convention )
$$ (50/110)/100 = 0.45455 \% $$