The following were just initial estimates of the causes of overhead. They happened to result in the overhead we assume for time-tracked research support, so we've left them. While originally intended for only the (time tracked) research support, there's no reason why it shouldn't apply to all work.
Being just rough average estimates, you can fill in your own values to determine your overhead more accurately. Follow the new value with an "enter" to cause totals to be recomputed. Force reload the page (usually shift reload) to reset to the defaults.