This curve is accomplishe by adding Curve 3 and Curve 1 together, where Curve 3 is used to drive the "OUTPUT" up early in the range and then Curve 1 is used to block it later in the range.
More specifically (with this design), the "INPUT" modified value is used to drive the "Upside" intermediate position by multiplying its impact 4 times (tying the "INPUT" modified value to the 4 supporting arguments of the "Upside" position). this value is then used to drive the "OUTPUT" upward toward 100%.
At the same time the "INPUT" modified value is being used to drive a "Reverser" to invert its impact and to provide a gradually increasing driver to the "Downside" intermediate position. In this case, the output from the "Reverser" is being amplified to the objecting arguments of the "Downside" position. This means the impact of the blocking capabilities are delayed until later in the "INPUT' range.