Acceptable Ta'wil refers to the meaning of a verse beyond its literal meaning;
rather the implicit meaning, which ultimately is known only to God and can't be comprehended directly through human thought alone.
Commentaries dealing with the zahir(outward aspects) of the text are called tafsir,
and hermeneutic and esoteric commentaries dealing with the batin are called Ta'wil("interpretation" or"explanation"),
which involves taking the text back to its beginning.