Steren CAL-150 Instructivo De Uso página 217

Afterwards, a perpendicular line will be drawn from the
same point on the graph to the y-axis.
First, locate the point on the graph using the Plot button,
afterwards, use the movement key to move the point
to the y-axis
The line function can only be used to draw lines between
the blinking point and a set point created by using the Plot
function