[WalterBright]

I gave several presentations that included this back in the 2010-2012 timeframe, and it had already been in the language for maybe a decade.

When I implemented it, I had seen many knock-down drag-out debates about which was the best way to deal with it, and none of them mentioned simply making it illegal.

It was another one of those features that were based on my experience designing aircraft systems.

Another one adopted by pretty much all languages since D is the _ in numeric literals (although C++ used a backtick). It was just something that was obviously right once you saw it. But I didn't originate it, I cribbed it from Ada. I've always had a soft spot for Ada.