[R] labels in multiple plot

[Bruno C.]

My code is the following:

point_type<-c("black","gray20","red"....)
...
for (i in 1:dim(m)[1]) {
                par(pch=(18+i))
                par(fg=point_type[i])
		plot(m[i,], type='b', ylim = c(lower, upper), type = "l", ...)
		par(new=T)
	}

Now I need to add an 'explanation'   to each pch. 
I would have a box in the upperright corner of the plot containing several rows each one in the format:
'pch symbol': 'explanation'

How can I do that? 

Thanx
Bruno