Hi Arjoo,
For Start of accrual (I) the "Start Account" is a balance sheet accrual account and "Target Account" is P/L account.
For Periodic accruals recognition (P) "Start Account" is P/L account and "Target Account" is B/S account
For Change of accrual start (U) "Start Account" is P/L account and "Target Account" is B/S account.
Thanks
Naseem