[R] spectum

[Bill Szkotnicki]

Hi,
In the help for spectrum it says:
"     If available, a confidence interval will be plotted by
     'plot.spec': this is asymmetric, and the width of the centre mark
     indicates the equivalent bandwidth. "

What you get is a blue bar on the right side of the plot.
I can understand the width of the centre mark.
But how does one make use of or interpret the bar itself?

What I would like to do is draw confidence curves on either side of the 
periodogram.
Is this possible or reasonable?

Bill