This excerpt taken from the PBI 10-K filed Mar 1, 2007.
Employers Accounting for Pensions, actual pension plan results that differ from our assumptions and estimates are accumulated and amortized over the estimated future working life of the plan participants and will therefore affect pension expense recognized and obligations recorded in future periods. We also base our net pension expense primarily on a market related valuation of plan assets. In accordance with this approach we recognize differences between the actual and expected return on plan assets primarily over a five-year period and as a result future pension expense will be impacted when these previously deferred gains or losses are recorded. See new accounting pronouncements below for the effect of SFAS No. 158,