Spaces within abbreviations, acronyms, and initials

Question

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!

Answer 1

Names generally have spaces between the initials because they are representing two names, but that's a matter of personal preference. k.d. lang uses periods but not spaces or capitals. e e cummings used spaces but not periods or capitals. J. K. Rowling uses all three. The company JPMorgan Chase uses capitals but no periods or spaces in the parent company name, but styles the brand name as J.P. Morgan.

P.S. and U.S.A. are abbreviations (I have often seen USA with no periods), and always function as a unit, so the spaces aren't necessary.