I have come across examples supporting both spaced as well as non-spaced examples and that's what confuses me. I want to understand what the standard practice is as endorsed by any of the major style guides. For example, consider the following examples:
A. B. Smith (Why is there a space?)
U.S.A (Why no space? And why no period after the "A"?)
P.S. (Why no space?)
I understand there already exists a similar question but since the answers on that one specifically deal with academic citations and Latin phrases, it doesn't help me. I am comfortable with Latin phrases, such as e.g., i.e., etc. not having spaces (P.S. being an exception because I still somehow see it as a regular abbreviation because it's capitalized, maybe? I don't know). It's the English acronyms that I find confusing... especially cases like U.S.A where even a period (the last one) is sometimes mysteriously omitted!