Accrual Start

Function Accrual Start within Bond with keys Bond Accrual Start keysreturns the start date of the accrual period of the referenced bond containing a given reference date Tˢ
Several values may be also returned here in the form of a 1D-array

If the settlement date Tˢ is not explicitly given, it will be set to the bond's settlement date as implied by a trade transaction assumed to occur on the trade dateT₀ (typically today).