Spell Difficulty and XP

[DavidMedley]

Are there any guiding principles for the spell difficulty (fail rates) and XP granted on first casting listed in class.txt? Are those numbers simply based on tradition, or is there some kind of formula at work that I'm not seeing?

[Monkey Face]

Fail rate is based on Intelligence (or Wisdom as appropriate) and character level.

XP gained from first casting has a fixed value for each spell and is greater for more difficult spells but is independent of fail rate.

[DavidMedley]

Sorry, I wasn't clear. I'll update my original post. I'm referring to the numbers in class.txt.