Thank you for your swift reply. But wouldn't that result in my removing all duplicate values? I'm trying to remove duplicates in a range and then look for the beginning of the next range and delete all duplicates but the first, and so on.

So
F
F
F
F

Becomes

F

But

F
F
F
x
x
x
F
F
F

Becomes

F
x
x
x
F

And so on. Does the filtering mechanism you point to allow for this? (If it does, I'm afraid I've missed it but I'll be happy to roll up my sleeves if you're sure it does.)

Thanks anyway for your help.