No need to emphasise the word 'try' in my post, Nigel: I very consciously put it in. But there are other ways to interpret the 'nothing is agreed until everything is agreed' clause. You can reach a conditional agreement, which is what was done with the green/amber/white sections of the last published document. A strict interpretation of the 'nothing agreed'line is that those colours mean nothing - all are equally 'not agreed'. But any sensible interpretation is that they are agreed to by different extents, even though all subject to a final sign off.