This is the correct version:
It limits the scroll position to the minimum and maximum coordinate you store in the values of the Multiple Touch object (set at the start of the frame in this example).
Note: the grey area in the example is the dimensions of the old iPhone device, it is only there for testing, it does *not* define the boundaries of the scroll area (only on that particular device). If you test this on an iPad with a different window size the scrolling area will be different. As I wrote before the limits for the scroll is completely configurable by setting the minScrollX, minScrollY, maxScrollX, maxScrollY alterable values in the Multiple Touch object.