can you write to files with unix format?

I am opening a file and line by line, writing its contents to a new file.

This is great. At a certain point i'm inserting a line return and some new text. I'm inserting the line return like this:

FileWriteByte $0 "13"
FileWriteByte $0 "10"

It works, but when you open it in notepad, you see the familiar ^M characters.

How can I do a line return that avoids the ^M stuff? Can I do something like:

FileWriteByte $0 "$\n"

?

FileWrite $0 "$\n"
(You also have $\r etc)

But using FileWriteByte with 13 or 10 should have the same effect (In the ANSI build)