Generally refers to roofing copper with tar, nails and a bit shingles. It also includes lead coated copper. As well as any copper that has significant contamination.
Is copper with solder, oxidation, corrosion, oil or thin platting. Stripped insulated wire with individual strands smaller then a paperclip is also considered # copper 2.
Is clean copper with little to no oxidation or corrosion. It should have no brass, solder or oil.