If you run
ls on a file or folder in OS X…
ls -la /dir/to/some_file_or_folder
You may see a permission entry like this:
-rwxr--r--@ 1 john admins 548 Oct 29 15:58 filename.plist
The at sign (@) means that the file has “extended attributes”. Extended attributes are basically some metadata that OS X and OS X apps can tack on to a file.
To view the extended attributes of a file, type:
xattr -l ./filename.ext