The class, as certified in December 2002, is defined as all former or current CIGNA employees who participated in the CIGNA Pension Plan before January 1, 1998, and have participated in the "Part B" CIGNA Pension Plan at any time since January 1, 1998.

In a traditional plan, benefits are based on formulas that multiply the number of years worked by a percentage of a worker's highest average salary--typically paid during the final years of employment. In cash balance plans, which have raised protests at many companies, the employer contributes a fixed percentage of a worker's annual pay to a cash-balance account.

The action alleges that CIGNA's conversion discriminated against older employees in the rate at which future benefits are earned. The cash balance plan allegedly forced employees to give up previously earned early retirement benefits in order to receive future contributions. In addition, the action alleges that CIGNA did not inform employees, as required by law, about the disadvantages posed by the pension plan.

Just when many midcareer CIGNA employees were entering the period in which they could earn benefits that were more generous under the traditional plan, the new formula was allegedly introduced. It allegedly provides enhanced benefits for young employees, but the middle-aged workers don't get them because the benefits are not retroactive.

Phrases that you should know:

Annuity: A retirement benefit that guarantees payment to an individual at some future time, generally beginning at age 65. The amount is often paid monthly. Pensions are a type of annuity, paid for the recipients' lifetime. A surviving spouse may continue to receive them. Privately purchased annuities often cover a limited time, such as 20 years.

Cash balance pension: A type of defined-benefit pension that can be paid as a lifelong annuity like a traditional pension. However, the employer that provides the retirement benefit calculates the benefit differently and illustrates the value to the employee in the form of an account balance. The account balance looks like a 401(k), but employees suffer no loss if retirement plan investments perform poorly. In a cash balance plan, workers often accumulate benefits at the same rate no matter how long they are employed. Cash balance plans also offer lump-sum payments, which are not usually available in traditional pension plans.

Defined-benefit plan: An employer-financed retirement plan whose benefits are guaranteed at the standard retirement age of 65.

Defined-contribution plan: A retirement plan that requires workers to set aside a portion of their wages for investment. Employees bear the investment risk.

401(k): A tax-deferred retirement plan that allows workers to contribute a percentage of their pre-tax salary for investment in stocks, bonds or other securities. Sometimes a company will match all or part of employees' contributions.

Lump sum: A one-time payment of retirement benefits.

Traditional pension: A benefit plan that a company or union contributes to while employees are working so the workers can receive a predetermined benefit, based on the time worked for a company and salary, for the rest of their lives upon retirement. Benefits increase as workers stay on the job longer.