I noticed that WordPress files use UNIX end-of-line and UTF-8 without BOM. Is this a standard that should be used? Is there anything else to pay attention to?
I noticed that Filezilla fails to transfer Macintosh end-of-line files properly to Windows or Linux servers. New line endings are missing. And sometimes they are doubled with different configuration. I’d like to avoid that if possible.
UNIX line endings (\n) and UTF-8 are just common code standards. As far as I can see, they are not even mentioned in the Coding Standards. Most (all?) core PHP files are just plain US-ASCII. Try to follow that path to keep your files as compatible as possible.
If you use UTF-8, add a line at the start of a PHP file with an Encoding Cookie or file variable:
<?php # -*- coding: utf-8 -*-
Many editors (Emacs, Vim, Sublime, Scite) will use that to set the proper encoding automatically.
I have also seen:
<?php # -*- coding: utf-8-unix -*-
But I am not sure how compatible it is.