29 C.F.R. § 4211.11

(a) General rule. A plan sponsor, other than the sponsor of a plan that primarily covers employees in the building and construction industry, may adopt by amendment, without the approval of PBGC, any of the statutory allocation methods and any of the modifications and simplified methods set forth in §§ 4211.12 through 4211.16.

(b) Building and construction industry plans. The plan sponsor of a plan that primarily covers employees in the building and construction industry may adopt by amendment, without the approval of PBGC, any of the modifications to the presumptive rule and simplified methods set forth in § 4211.12 and §§ 4211.14 through 4211.16.