Middle softkey labelling
From S60 3rd Edition, Feature Pack 2 onwards, middle softkey (MSK) labelling is included with the S60 UI interaction mechanism. The "middle softkey" is also called the Selection key. The additional softkey labelling enables improved access to application features by offering more opportunities for function access.
Figure: The middle softkey
For more information on how to make use of MSK for your applications, see: