29 C.F.R. § 4211.11

(a) General rule. A plan, other than a plan that primarily covers employees in the building and construction industry, may adopt, by amendment, any of the statutory allocation methods and any of the modifications set forth in §§ 4211.12 and 4211.13, without the approval of the PBGC.

(b) Building and construction industry plans. A plan that primarily covers employees in the building and construction industry may adopt, by amendment, any of the modifications to the presumptive rule set forth in § 4211.12 without the approval of the PBGC.