Tempting as it is to raise a conundrum about the NPPF, we're well aware that CIL is still causing plenty of headaches as we all seek to understand how this will work in reality. One of the concerns that we have heard raised by a number of developers relates to viability. Of course, this will be taken into account when the CIL rate is set, but viability can change on an almost daily basis and changing a CIL rate is likely to take months, if not years. Is there a real risk that CIL will not be able to keep up with fluctuations in market conditions and so risk scheme viability?