Alan wrote in
:

I am curious as to why they don't seem to use the name Robertson any
more, but call them square drive instead. Wouldn't that be like
calling Phillips, + drive?

Robertson is a brand (and company) name -- they are the only ones allowed
to use that name. Now that the original patent has expired, anyone can
build screws and screwdrivers, but they still have no choice but to use a
generic term such as "square drive".

For what it's worth, I still buy Robertson brand tools and screws whenever
possible -- their quality is excellent. Lots of knock-off "square drive"
screwdrivers (and screws) are complete junk.