It generally follows the escape rule of string in Elisp I think.

At 2020-10-05 15:39:54, "Lars Ingebrigtsen" <larsi@gnus.org> wrote:
>Eli Zaretskii <eliz@gnu.org> writes:
>
>> I think this would have unwanted effect on other control characters.
>> ISTR this was discussed in the past, but I cannot find that discussion
>> at the moment.
>
>I experimented a bit with two files, one with a newline and one with a
>C-b character:
>