For formatting purposes it is best to use the following commands before calling the plot15 function (savePath is the pathname for directory to store the output)
# plotName <- paste(savePath, "plot15.", eList$INFO$shortName, ".ps", sep = "")
# postscript(file = plotName, width = 8, height = 10, horizontal = FALSE, family = "Helvetica")
Then after running plot15, the user needs to give the command dev.off()