Other modifiers to the various checks come in the form of Abilities. An Ability represents a field of expertise or knowledge that the character is proficient in and can help when conducting operations or negotiations in that area. Combat is one such Ability as are things like Agriculture, Economics, History or Medicine. Some Abilities are likely to be more common than others to be taken but the ST is the final arbiter on whether any particular skill is a valid option for their game.
Abilities generally run on an exponential scale from 0 to 3. However, certain situations or Talents can cause you to have a negative value which then applies as a penalty to a relevant check. Characters cannot start with a negative value in an Ability unless with ST permission or acquisition of a Talent that permits it.
The general scale for Abilities is:
-1 = spectacularly bad or incompetent for some reason.
0 = average level of the general populace, possibly basic understanding for non-scholastic areas depending on society norms.
1 = skilled / competent above average levels, represents some training (not necessarily formal) or aptitude, or the character has taken a particular interest in it. Also, probably the character’s profession or primary means of survival.
2 = expert or highly skilled, probably applies to a teacher of such as well.
3 = professor or grandmaster, one of the foremost practitioners of the ability or foremost minds on the subject.