And for the historical explanation for why these filenames are special even with an extension, see https://devblogs.microsoft.com/oldnewthing/20031022-00/?p=420

And for the historical explanation for why these filenames are special even with an extension, see https://devblogs.microsoft.com/oldnewthing/20031022-00/?p=42073 https://devblogs.microsoft.com/oldnewthing/20031022-00/?p=42... "Suppose you wanted the listing file to go straight to the printer. [...] So you typed “PRN” as the filename. Now, the assembler doesn’t know about these magic filenames. So the assembler will try to create the file “PRN.LST” and then start writing to it. Little does the assembler realize that the output is actually going to the printer." Windows path handling is full of special cases and subtle gotchas. See https://googleprojectzero.blogspot.com/2016/02/the-definitive-guide-on-win32-to-nt.html https://googleprojectzero.blogspot.com/2016/02/the-definitiv... for a very detailed list.