A MOD (or in the test case a smileys pack --> http://custom.simplemachines.org/mods/index.php?mod=2125) fails to (by returning "Modification Parse Error"):
a) properly handle require-dir if the folder to copy is empty AND the package is zipped. This means that if I unpack the package to a folder inside Packages and try to install it (instead of it being a zip file) it will install properly
b) properly handle create-dir. It seems not to work in any case, as it always returns "Modification Parse Error.