In the components of net periodic benefit costs...

is net loss (gain)

1) unrecognized (gain) loss / future years of service

or

2) the difference between the actual return on plan assets and the expected return

There are two components. (1) amortization of recognized accumulated gains/loss, which include asset gain/losses but other gain/losses as well. The amount that is amortized depends upon the method of amortization selected and could be what you suggested. (2) The difference between expected return and actual return shows up as deferred for later recognition.

An example will help explain (2). Assets 1/1/2008 = 1,000,000. Expected long-term rate of return = 7%. Expected return $70,000. The $70,000 is used to determine 2008 expense. Suppose the actual return is $80,000. Then, expense would show ($80,000) as the actual return and then show $10,000 as deferred for later recognition. In short, pension expense is determined without regard to the year's actual investment performance.

thank you very much.