Key Tenor in refers to the rate's "spanning period" Δ that - in a given context - implies the "spanning time interval" [T₁,T₂], as described at
The exact start and end dates of that interval are also determined by the settlement conventions defined in
Expects an object of type .
It is possible to leave this entry undefined, in which case Δ becomes context-dependent and is assumed to equal the applicable accrual period where the rate here is used.
This is - for example - the case of used as the floating index in an , where it is often desirable that the respective overnight index is compounded over a spanning period that either matches or derived from the corresponding accrual period of a given floating leg.