The Swap Rate displays the projected floating rate, i.e., the future floating rate based on the average of the current values of the futures over the swap period.
For a spread swap 3-leg and a spread swap 3-leg strip this field displays the actual spread, which is always displayed in the unit of asset 1 and is calculated as follows:
The swap rate of Asset 1 +/- the swap rate of Asset 2 +/- the swap rate of Asset 3
The swap rate of each individual asset is calculated as its weight x its price, where for asset 2 & asset 3 the inclusion of the weight lets SD convert the swap rate of that asset in its own default unit into a swap rate in the default unit of asset 1.