Alternatively, maybe it's a random set of letters the user inserted accidentally. Maybe they wanted to say "SVTFOE" as some code for the story. Since I can't figure it out, maybe I should focus on making it part of the story. Maybe the magic book has an unlock code "svtfoe" to access exclusive spells. That could work. Or maybe it's part of the title in the story, like "The Magic Book of Spells: SVTFOE Edition."