So after E, it's A for 'Acceptable,' and that's the last pass grade, isn't...

So after E, it's A for 'Acceptable,' and that's the last pass grade, isn't it?"
"Yep," said Fred, dunking an entire roll in his soup, transferring it to his mouth, and swallowing it whole. "Then you get P for 'Poor' " - Ron raised both his arms in mock celebration - "and D for 'Dreadful.' "
"And then T," George reminded him.
"T?" asked Hermione, looking appalled. "Even lower than a D? What on earth does that stand for?"
" 'Troll,' " said George promptly.