utility of this field: "Accrual Rule Data Effective Date" TIME ACCOUNT TYPE

Hello colleagues,

I do not really get the utility of this fields and its impact in the resto of the system it is a time account type field "Accrual Rule Data Effective Date"

the options are Accruable Start Date and " End Date but this same 2 options are inside of the hire, accrual and termination rule so it is inside of the rule where you select this, i don´t know the sense of having this field outside.

Does anybody know what is the real effect of this field?

Regards