Multi-panel titles in R

I have an ultra short question about R

My aim is to assign a common title to a multi-panel plot generated using par, e.g.

par(mfrow=c(1,2))
plot(rnorm(1000))
plot(rnorm(1000))

So, something like "mai开发者_StackOverflow中文版n" for the plot function, but extended to both plots. Is there a canonical way to do this?

Thanks for any answer :-)

---

Use mtext with option outer:

set.seed(42)
oldpar <- par(mfrow=c(1,2), mar=c(3,3,1,1), oma=c(0,0,3,1))  ## oma creates space 
plot(cumsum(rnorm(100)), type='l', main="Plot A")
plot(cumsum(rnorm(100)), type='l', main="Plot B")
mtext("Now isn't this random", side=3, line=1, outer=TRUE, cex=2, font=2)
par(oldpar)