[R] Adding a symbol/value/overlay to a boxplot in R

[Marc Giombetti]

Hello everybody,

I am new to R and I am having the following problem.
I have the following boxplot:

boxplot(s$Estimate,u$Estimate,names=c("Security", "Usability"))
title(main="Estimated development time",ylab="Estimate (weeks)")

http://i35.tinypic.com/2rhw9rm.jpg

but I want to add a label or symbol for a specific value to every
boxplot. I uploaded a screenshot
of a boxplot I generated using Excel which I try to replicate using R.
In this example, I want to compare my dataset"usability" to a single
value 84 (which is not part of u$Estimate). Is there a way to add a
special symbol/value to every boxplot? Some kind of overlay layer?

http://i35.tinypic.com/24n0020.jpg

I appreciate your help!

Thanks a lot,
Marc