Take these two headlines:
MLB RESULTS FOR FRIDAY
MLB Results For Friday
You can’t do Title Case on the first because it’s already all caps. So you would lowercase it first. But when you do that, you lose the acronym.
You can do Title Case on the second without losing the acronym, though.
The improved Title Case does look at the text to see if it has any lowercase letters. If not, it lowercases the text:
$_ = lc $_ if not /[[:lower:]]/;
That still loses the acronym but at least it edits the text. You just have to restore the acronym. And if the string is not all caps, you’re fine.
(I’d been using the built-in Title Case after a Lowercase and forgot about that Lowercase when I said the improved macro handled acronyms and Title Case didn’t. I was killing the acronyms that Title Case would have left alone.)
Hope the clarifies things.