When is stored in a Vim variable/register/etc, it is stored as a NULL, and then translated back to a real newline under circumstances such as "put". Try inserting a newline in insert mode, i.e. ^V^J (or ^Q^J if you're using the mswin behavior). You will see a <00> show up. Now try these to help understand further: let @a = "a" . " " . "b" or let @a = "a" . "\x0a" . "b" and put it into the buffer using "ap or :put a You should see: a b "put" is especially smart about translating the newlines from NULLs back to 0x0a. Now do: call setline(".", @a) or call append("$", @a) You should see: