Multi-employer (benefit) plans are defined contribution plans (other than state plans) or defined benefit plans (other than state plans) that:
(a) pool the assets contributed by various entities that are not under common control; and
(b) use those assets to provide benefits to employees of more than one entity, on the basis that contribution and benefit levels are determined without regard to the identity of the entity that employs the employees concerned.
Multi-employer (benefit) plans are specifically discussed in IAS 19 Employee Benefits.
Source: Glossary of Terms of IFRSs as at 31 December 2008.