S60 UI with side softkeys assumes a hardware that has the softkeys on either side of the display. A product concept for such a case might be, for example, a device optimized for using some specific applications in a 90 (or 270) degrees rotated mode, but not having extra keys for providing the softkey functionality in the bottom of the display in this rotated mode. Note that the landscape orientation also works with bottom softkeys in devices with that type of an aspect ratio.
Thus, the softkeys in this mode are on either side of the UI depending on the hardware and its mode.
Figure: Example images of S60 UI with side softkeys (right rotation)
The side softkey style assumes the same keys as the default S60 UI.
These style guidelines make no assumptions about the display resolution, the exact aspect ratio between the height and width of the UI, or the pixel density of the UI. However, the assumption is that the side softkey style is applied in either a landscape (width > height) or a square (width = height) display mode, but not in a portrait display mode (width < height).