open C, closed C ??

In Cecil’s column on chocolate squiggles, what exactly is an “open C” and a “closed C”. I would have thought every C was open – otherwise it’d be more like a backwards D.

I’d hate to think I was getting chocolate cream and end up with cherry cordial.

I was wondering exactly the same thing.

After all, I’d hate to be expecting a cherry cordial and end up with a chocolate cream.

This numismatic site shows examples of open and closed Cs. Row 7, about halfway down.

OK, so an open C is what I probably would have called a “broken” C, i.e. a C with a gap in it. Right?

I guess so. I was wondering, too, so I googled it. That was the best answer I came up with in the first twenty hits.