wrote:
There is a plywood that is about 1/2" thick and has grooves in it, with
a rough surface. It's sort of a paneling for exterior use as siding.
What is the trade name for this product?

Others have already mentioned T1-11, but I figured I'd add this just in
case what you are asking about is not really plywood.

About 1/2 inch thick, grooves and rough surface...could be an engineered
product, one example of which is Smartside:

http://www.lpcorp.com/smartside

It comes in planks, panels and trim and is typically made of wood strands
impregnated with anti-fungal and anti-insect additives.

Smartside is just one brand name, there are others. I have a shed sided and
trimmed with the product. Just this morning I watched an episode of How's
It Made where they showed the manufacturing process of the product.