What if "value" is already an array - and then in addition an array which itself contains expanders? In that case, this prefix of "0" will be incorrect. Also, we can't just special-case fluid.transforms.arrayValue in this way - the same logic must be operated for every transformer which returns an array. In theory we could still salvage this implementation, but it will need a lot more work than this. Right now at least the behaviour we have in trunk is consistent even if it is sometimes unhelpful. The idea of "modify the outputPath to denote that we're now in an array" can't be made into a consistent one.