Hi Mark,

I have spent the last couple of hours looking at your code and I cant work it out, if you could place a few text pointers around that would be great.

A few things, why the group by (min base) and why s1.top <= t1.base

I am sorry I am stupid but there are two many steps removed for me to learn how you came up with this.

Sorry to be a pain.

Many Thanks,

Oliver