Under ERISA Sec. 101(l)(1)(B), which I believe was added by PPA, the plan must disclose to a participating employer an explanation of how estimated WDL was determined, including "the actuarial assumptions and methods..., the data regarding employer contributions, unfunded vested benefits, annual changes in the plan's UVB..." Two questions: how much detail do plans generally provide for the "explanation"? and does the reference to "the data regarding" refer to employer contributions only, or to UVB and other items mentioned? In particular, does an employer have a right to all participant data to attempt to reproduce the plan's calculation of UVB?