Here is a simple illustration of one way to do this:
Names Default To Here( 1 );
dt = Open( "$SAMPLE_DATA\big class.jmp" );
// Create reference line data table for the illustration
dtLines = New Table( "Lines",
New Column( "HeightRefs", values( [52, 60, 66] ) ),
New Column( "Labels", character, values( {"Age 10", "Age 14", "Age 18"} ) )
);
// Create the chart
Biv = dt << Bivariate( Y( :weight ), X( :height ) );
// Add the lines
For( i = 1, i <= N Rows( dtLines ), i++,
Report( Biv )[AxisBox( 2 )] << add ref line( dtLines:HeightRefs[i], dtLines:Labels[i] )
);
Jim