It's been 10 years since the first "Harry Potter" book hit stores in the U.S. as of Tuesday (September 23), but J.K. Rowling didn't make this journey all on her own. Just like her boy wizard, she's had help along the way.

The author's team of editors, both in the U.K. and the U.S., kept watch on the seven-book series so nothing too big or small went unnoticed — and on the off chance something did slip through, her readers were even more vigilant.

"Marcus Flint, who is the Slytherin Quidditch captain in books one and two, appears again in book three," said Cheryl Klein, a senior editor at Arthur A. Levine Books, the Scholastic imprint that publishes the "Harry Potter" series in the U.S. "But he was said to be a sixth-year student in book one, which meant he should have graduated by book three. So that gave rise to this entire category of what we call 'Flints,' when fans find continuity errors after the fact."

Klein is what is known as a "continuity editor." It's her job to keep track of everything that happens in the series, to make sure things are consistent and the details are right. But the letters she gets from the fans sometimes help.

"It's like having 6 million copy editors checking your work," Klein said. "We really handle everything on a case-by-case basis, and we ask, for every letter, 'Have we dealt with this before? Is this a valid concern?' And some we fix ourselves, and others we talk to our British colleagues and J.K. Rowling."

Some "mistakes" are just cases of British-to-American English translations — like how in the U.K. version, there can be both a ground floor as well as a first floor for the Ministry of Magic, as opposed to the U.S. version, in which the first floor opens out into the street. "At first, we changed a lot, because people didn't know what was British versus just the magical world," Klein said. "So as they got more and more familiar with it, we didn't need to worry about that as much."

Some letters are more about concerns of usage versus actual mistakes. "This one woman I met, her daughter had a cleft palate," Klein said. "And in book two, Gilderoy Lockhart referred to doing something with a 'hag with a harelip.' J.K. Rowling was using that phrase to indicate Gilderoy's insensitivity, because he doesn't really think about anybody besides himself, but when she realized that it's a phrase that some people think is less than acceptable for people with cleft palates, she changed it to a 'hag with a hairy chin.' "

Another phrase that brought complaints was from book five, when Hagrid told Harry and Ron — to encourage them — "Keep your peckers up." "We couldn't keep that in," Klein laughed. "So we changed that to 'Keep your chins up.' "

That doesn't mean Rowling's editors change every questionable phrase once they get a letter of complaint — far from it. "At one point, Uncle Vernon was speaking, and so the text said, 'Uncle Vernon ejaculated,' " Klein recalled. "That's actually a good speech verb. It means you spit something out very fast. People wrote to us and asked us to change that, but I don't think we did."

Fans also asked about the timeline, since at one point, Dudley gets a PlayStation. "It didn't come out until later, if you date the series chronologically. If you say Nearly Headless Nick's Deathday celebration is in 1992 ... ," Klein stopped herself and laughed. "This is really dorky stuff."

So dorky that fellow (albeit self-appointed) keepers of the "Potter" continuity like to tease Klein about mistakes made in the books that may not have actually been made, just to watch her head spin. John Noe, from the Leaky Cauldron, for instance, likes to tease her that the plural of Horcrux was stated once as Horcrii — "and I'm like, 'No, no, we didn't!' " she said, imitating panic in her voice. "But then I checked with J.K. Rowling, and she assured me, 'No, no, they're Horcruxes.' "

And all was right with the "Potter" world once more.

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