Lets in two classes of inventions, invention can be set up either way (or both).
1.    Products: Machines, composition of matter, manufacture is catchall–gets everything else.
2.    Processes = Process art or method and includes a new use of a known process, machine, manufacture, composition of matter, or material.  100.
a.    2 flavors.
(A)    Method of using something: how to use an item.
(1)    If you discover a new use for a patented product, you can patent the new use but are blocked by the patent holder of the product. Holder of patented product is blocked from your patented use.
(2)    No permission needed from original patent holder to develop the new use.
(B)    Method of making the item.
b.    AT&T v Excel: (C2P197) So long as process is “useful, concrete, and tangible” doesn’t have to be physical. Broad.
c.    If you describe product by a process, you only protect the process. But can protect product later on. May be strategy for only revealing process and not the product.