Men's vs. women's toilet seats

Dear Matthew Alice: The following has been puzzling me for some time now. I have asked numerous friends, and none of them have been able to supply a reasonable response. Why do commercial restroom toilets have a “notch” taken out of them? You know, the one in the front of the seat that transforms them from an O into a U. If the seats were only in men’s toilets, I could understand it to be a streamway, but since they’re in both men’s and women’s, it really doesn’t make sense. — Jovino, San Diego

I have it on good authority that there is a sign in the ladies’ room of the palatial Reader offices that says, “Be a sweetie. Wipe the seatie.” Do we see the flaw in our original reasoning, Jovino?