I have been operating under the assumption that the number you can assign to lookup data features is the character level at which to apply that feature. However, testing it now, I haven't been able to get it to work. I added a feature to a heritage with the level set to 5, but upon levelling a character with that heritage to level 5 the feature is not added.
Have I misunderstood what that field is for, or is something not working?