A few summary functions used by ggplot2

I could not quite figure out what the summary function "mean_sdl" stands for, so I took at a look at the source code "stat-summary.r". It turns out that this is a wrapper function of the "smean_sdl()" of the Hmisc package, as well as the "median_hilow", "mean_cl_normal" and "mean_cl_boot".