LH you are of course correct, the square drive screw, invented by Canadian P L Robertson is by far the best (as I said in my previous post).

But, I have always wondered why it is not generically referred to as a "Robertson" screw, in the same way as a "Phillips" or "Allen" screw.

I used them every day for two years while working in Boston, but I never heard anybody refer to them as anything but "square -drive" screws.

Murray