I can't use has_not_created, as it's possible to read the parchment without removing it from the tin box. Instead, I set a boolean the first time it's read and the magic word only takes effect if the boolean is set (i.e. if the parchment has been read). This is hinted at with an extended message the first time the parchment is read. I had been thinking about doing this anyway, but your suggestion prompted me to implement it. Thank you.