chr(10) is "line feed" (LF)
chr(13) is "carriage return" (CR)

this is why the kix macro is called crlf
theses two characters are usually used as the end of line in text files on Microsoft OS.

on Unix, the end of line character is LF

example for messagebox with kix 3.6x

$crlf = chr(13)+chr(10)
$=messagebox(
"the first line"+$crlf+
"the second line"+$crlf+
$crlf+
"the last line",
"the title,
0
)
_________________________
Christophe