Calculation of Withdrawal liability

[ERISA25]

Is this the GENERAL procedure for calculating withdrawal liability: (1) withdrawal liabiilty determined under a method provided in ERISA Section 4211 (this is the actual W/L amount); (2) That amount is amortized over a number of years in accordance with ERISA Section 4219.

It seems to me that an employer wanting to pay W/L in a lump sum payment would pay the amount that is determined under Section 4211. There would not be any type of discount for paying in a lump sum payment. Is this correct? Please let me know if you know of any cases/PBGC opininons, etc., that discuss lump sum withdrawal liabiilty payments. Thanks.