The following terms are defined in § 4001.2 of this chapter: ERISA, IRS, multiemployer plan, PBGC, plan, and plan sponsor.

In addition, for purposes of this part:

Arbitrator means an individual or panel of individuals selected according to this part to decide a dispute concerning withdrawal liability.

Employer means an individual, partnership, corporation or other entity against which a plan sponsor has made a demand for payment of withdrawal liability pursuant to section 4219(b)(1) of ERISA.

Party or parties means the employer and the plan sponsor involved in a withdrawal liability dispute.

Withdrawal liability dispute means a dispute described in § 4221.1(a) of this chapter.