The <newline> character can also be an "IFS whitespace character"

[ziyunfei]

Quoting from the bash manual: 

"If IFS has a value other than the default, then sequences of the whitespace 
characters *space and tab* are ignored at the beginning and end of the word, as 
long as the whitespace character is in the value of IFS (an IFS whitespace 
character)."

If this is true, then the following script

$ IFS=$'\n'
$ a=$'\n1\n2\n'
$ printf "%s\n" $a
1
2

should print <> <1> <2> 3 fields, but it doesn't.

So I guess *space and tab* should be replace by *space, tab and newline* in 
that section.