4221.2—Definitions.
         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.