New Belgium plus a considerable number of homebrewers use the spelling "Graff". I am a huge Stephen King / Dark Tower nerd, so I spell it like he does in the series, Graf. I don't know enough about its history to know if the name was entirely his invention or he found something similar in research, but I believe it's just made-up and probably akin to the phrase grog. I make mine with 4 gallons of apple juice for a five gallon batch and usually aim for a low FG and around 9% ABV. In the books, the characters remark that it can be quite strong, but isn't always made that way.