Here's a new one on me: A reader who went to parochial school tells me a nun was "very adamant" about the idea that people's names used in apposition should not be set off with commas, because that would risk confusion with direct address.
In other words, you'd have to say "My mother Mary is at home," because "My mother, Mary, is at home" would be telling someone named Mary that your mother was at home.
Anyone else ever heard of this wacky "rule"?
It's absurd, of course, for a number of reasons. (Even if all your readers were named Mary, most would presumably realize you weren't writing directly to them.) But I suppose some people would roll their eyes at the logic most of us apply -- using commas if we have one mother and no commas if we have two or more.