If you have seen the first post of the same name, an error was present. I have seen a coin on USA Coin Book that looks like it's been self-slabbed. It's an 1891 Seated Liberty Dime graded by PGS at "VG-10, Corrosion". PGS apparently stands for Professional Grading Service, and I wonder why it wouldn't say VG-10 Details. What makes me suspect it is that the slab appears to be not sonically sealed, possibly a BCW coin slab. They did list it as corroded, though. If you have any information on this grading company, please let me know as I am looking to learn as much as possible about grading services.