Skill set/modify effects

By JSKNYC, in L5R LCG: Rules Discussion

I'm wondering if someone might be able to clarify how multiple concurrent effects modifying a character's military and political skill values derive actual current values. I come from a Magic: The Gathering judging background; I've generally treated such stacking effects in L5R the same way MTG's layering system handles them. It's my understanding now, though, that I've been mistaken. Is there a concise paradigm anywhere that I could take a look at? I'm not convinced I've got a thorough understanding, after reading the Rules Reference.