PlainEnglish is written for newbies. I am one. I understand horizontal lines, but why would one ever use brackets spanning paragraphs? This just comes out of nowhere. Perhaps edit to say something about ProperUsageOfBrackets before the point about brackets spanning paragraphs?

[Some people tend to like to put inline comments in brackets. This is usually only mildly annoying. But when the paragraphs then span lines, it becomes an actual pain to read.

Perhaps it's in reaction to the Wiki convention that ''italics'' implicitly end at the end of a paragraph; if you try to write a two-paragraph inline comment, and encase the entire comment with two single quotes, your comment ends up looking like an italicized response, then a response to your response.

Quick now - were the above two bracketed paragraphs written by the same author? Or is the second one answering the first? And is this a third comment, or the end of the whole thing? Ahh.... here comes the end bracket. Must have been all written by the same person.]

... but when
Similarly, I don't get the example above that refers to [[[NewRefactoringInstruction]]]. For example, 
what in the world is a "space line"?

Thanks.

I'm not sure I understood the part about the brackets either,
but I assumed a 'space line' to be an empty line separating two paragraphs. -- TyberiusPrime

''Ahhhh. Of course. Where I'm from (here in the U.S.A.) we call that a 'blank line'. Thanks.''
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''Must have been all written by the same person.''

This is the preferred way to do anything besides a very short inline comment. The commentary is separated from the main content by a horizontal bar; a short (optional) reference is included in italics, if it's needed, and the comment itself is normally formatted, in plain language, with no extraneous brackets in sight.