The following terms are defined in § 4001.2 of this chapter: employer, ERISA, IRS, Multiemployer Act, multiemployer plan, nonforfeitable benefit, PBGC, plan, and plan year.

In addition, for purposes of this part:

Complete withdrawal means a complete withdrawal as described in section 4203 of ERISA.

Eligible employer means the employer, as defined in section 4001(b) of ERISA, as it existed on the date of its initial partial or complete withdrawal, as applicable. An eligible employer shall continue to be an eligible employer notwithstanding the occurrence of any of the following events:

(1) A restoration involving a mere change in identity, form or place of organization, however effected;

(2) A reorganization involving a liquidation into a parent corporation;

(3) A merger, consolidation or division solely between (or among) trades or businesses (whether or not incorporated) of the employer; or

(4) An acquisition by or of, or a merger or combination with another trade or business.

Partial withdrawal means a partial withdrawal as described in section 4205 of ERISA.

Period of withdrawal means the plan year in which the employer completely withdrew from the plan, the plan year in which the employer reentered the plan and all intervening plan years.

Unfunded vested benefits means, as described in section 4213(c) of ERISA, the amount by which the value of nonforfeitable benefits under the plan exceeds the value of the assets of the plan.