I just ordered and received several Carlton File-o-Plates. On an old training video(made in the 80's) where I work, the guy showed one for filing the depth guages/rakers. But looking at the thing, there are holes that I don't know what they're for. Carlton doesn't seem to offer much instruction on them...can anyone offer a small crash course on these? I'd really like to use all the cool stuff on it... thanks for helping out a beginner.