What does these extended attributes mean and where are they documented?
All commandline apps have an associated man page, that explain input and output, invoked like this:

man [command]


Where [command] is the command you want help on. So to find info on ls:

man ls


Also Mac OS is based on BSD unix and not completely different from Linux. So googling for the man page on almost any (BSD/Linux) unix command will also lead you to (quite possibly) more info that you can possibly digest...