For trend operations such as compressing and expanding a trend, you
must first select the trend.
Click the parameter reference in the Legend or click the
associated small faceplate. (Tip Notice that an asterisk appears between
the color indicator and the trend name on the Legend and the trend is
highlighted on thegraph.)
To select multiple trends, hold down the SHIFT key, and then
select the trends.
Press the CTRL key as you click the parameter reference.