ambiguous sentence in documentation

Quote from QVariant Class Reference:
"bool QVariant::toBool () const
[...]
Returns true if the variant has type() Bool, Char, Double, Int, LongLong, UInt, or ULongLong and the value is non-zero, or if the variant has type String or ByteArray and its lower-case content is not empty, "0" or "false"; otherwise returns false."

This is ambiguous, because it's not clear if you mean: (Heed the brackets in the sentences)
1) Returns true if the variant has type() Bool, Char, Double, Int, LongLong, UInt, or ULongLong and the value is non-zero, or if the variant has type String or ByteArray and its lower-case content is (not empty), "0" or "false"; otherwise returns false."

or

2) Returns true if the variant has type() Bool, Char, Double, Int, LongLong, UInt, or ULongLong and the value is non-zero, or if the variant has type String or ByteArray and its lower-case content is not (empty, "0" or "false"); otherwise returns false."

I know myself that brackets are only coder style and not a good "normal" text style, but i don't know a better solution if the sentences should stay short.