415(e) and terminated DB Plans

[KJohnson]

An employer maintianing a DC Plan indicates that they had a DB Plan which terminated in June 1994. I have calculations of the annual accrued benefit at NRA for each participant at the time of plan termination and the lump sum benefit using PBGC rates (each participant elected this lump sum option). I also have years of service under the Plan, "high three" compensation data, as well as birth and normal retirement dates.

Could someone walk me through how I get to the 415(e) DB fraction--particularly with regard to the lump sum distributions, pre-social security age distributions and distributions to participants will less than 10 years of service?