IF you intend to give this file to a user of a Mac it should have Mac line endings
IF you intend to give this file to a user of Windows it should have Windows line endings
And maybe you have an option to export it to a format for the other OS
Any Mac program would reasonably expect you use proper mac line endings
And a Windows app would reasonably assume you used Windows line endings
I do own text editors that do NOT automatically translate line endings - they preserve them
But if you’re writing this for your own program to read & write on either platform you can do it in a way that you don’t have to care and can use it regardless of what line endings it has
And if you hand a file with CR+LF to a Mac user they may get doubled up line endings or worse - the behavior time noted
However since it IS possible to make a Xojo written app not care which one you’ve used its easier to make your app nicer by accepting either style