A pension or OPEB plan to which two or more unrelated employers contribute, usually pursuant to a collective bargaining agreement, is generally considered to be a multiemployer plan. A common characteristic of a multiemployer plan is that there is no separate accounting for assets contributed by the participating employers. Instead, the assets are commingled and can be used to provide benefits to employees of other participating employers. Contributions to the plan may be on the basis of production, hours worked, or similar criteria. The plan frequently is administered jointly by labor and management trustees. See PEB 5 for a discussion on the accounting for multiemployer plans, and distinguishing between multiemployer and multiple-employer plans.