The Overview display shows one Parameter representative of the Block.  For example, the Absolute Deviation Parameter of a PID Block is usually shown on the Overview to indicate near normal (a small value) or abnormal (a large value).  In version 2.1, the default Overview display is text only; it could easily be replaced with a graphical display or bar type display.

Overview in Parameter Properties will in a future release define whether this Parameter will appear in the Overview Display.  The Overview Display is a standard system display that provides a summary of all the Faceplate Groups including Blocks.