ما معنى Compounding in arrears؟

Over an interest period of $N$ calendar days with business days $d_1, \dots, d_M$, fixings $r_1, \dots, r_M$ and weights $n_i$, the calendar days from $d_i$ to the next business day, the rate compounded in arrears is

with $B = 360$ for the dollar and euro and 365 for sterling. It is known only after the last fixing. Three conventions bring the payment date forward: a lookback of $p$ business days uses $r$ from $p$ days before each $d_i$ with the period’s own weights; an observation shift takes rates and weights from a period moved back by $p$ business days; a lockout freezes the last $k$ fixings at the one before them.