For the most part, Trinity uses the same standard d20 ability scores as found in other systems. However, in order to ensure that firearms are balanced, a new ability score - Perception - has been added.
Also, to further reflect education, sometimes an Education score may be used. Unlike other ability scores, Education is modified by your character's home region, not your race.
However, sometimes, those eight ability scores may not be enough. If you are playing in Trinity with a new player, or want to help players in their roleplaying - even if you're not playing in Trinity - you may want to consider the REASS.