[Section103]

....they're all pretty much the same

6 Surface: Noticeable print spots. Minor color or focus imperfections. Minor border discoloration and color or focus imperfections. Minor wax stains or extremely subtle ink marks. Relatively solid gloss with minor scratches, but devoid of scuffing. Noticeable metallic print lines.
4 Surface: Heavy print spots. Hairline creases. Moderate color or focus imperfections. Moderate border discoloration. Moderate wax stains. Very light ink mark or tape stain. A good deal of gloss lost from surface. Very minor scuffing or an extremely subtle tear in the form of a touch of broken surface paper.

Hairline creases start at 4. With that said, Im reminded of the fact that lots of sellers on eBay use their own grading standards (same numbers, same abbreviations) which differ greatly from the standards.