This is a clarification post, and seeing if I'm missing anything.
XP advancement seems to be in a few stages:
Base source quality: Read a tractatus, SQ 9
Advancement Total (flat): Applied modifiers from as virtues. Book Learner, changes SQ from 9 to 12.
Advancement total (percent): Affinity and Linguist, etc. Affinity with Art, changes from SQ 12 to AT of 18
XP gain: The advancement total turns into XP. This is where Elemental Magic and Secondary Insight get applied, I believe. Also, any flat xp bonuses from Twilight Experiences, Lab Experimentation, or other non-seasonal steps jump straight to here, do not apply Affinity, do not collect $200.
While it makes sense to me to apply the flat before the percent, it also isn't explicitly stated.. it just says apply 'bonuses from virtues' in my book (Core p163). If you apply things the other direction you get 9 + (9 * .5 = round 5) + (3) = 17xp.
And as a note, Book Learner gets around this by explicitly changing the source quality of the book you read, rather than giving you an advancement total, and Free Study gives a similar bonus to studying from Vis.
Sounds like you have it right. Bonuses to Quality apply to calculate the Advancement/Study Total. This then gets multiplied. Then you get experience from it. That can then trigger some bonus experience. But bonus experience rarely triggers anything at all. This way order of operations is kept working mostly smoothly.
I say "rarely" and "mostly" because Flawless Magic accidentally was written differently and in a way that could seriously mess with order of operations, though because it only works in a particular spot I'm not sure it actually ever makes a mess. I'm pretty sure I submitted Flawless Magic to the errata request because of this. I know I submitted a bunch of accidentally remaining "Study Total" listings.
Hi! Because they are not xps derived from study totals, they do not fall within the specifics of Affinities. They are bonus, extra, even if you only earned exposure study xps that Season. You could house rule it, one imagines.
It does feel kind of silly to have confirmation on a basic thing like xp assignments, but during our board's big David Chart shindig, I decided it was good to finally ask this question aloud - as I mentioned, some of the things I've seen on the boards or in discussion with people have had.. fun interpretations.
I'm looking at you, Elemental Magic discussion that first got me posting on the forums...
That is weird. I agree. I hate it though. So much simpler to just have Affinity multiply all XP in its skill/art rather than distinguishing between different sources. But eh. Probably not a huge difference one way or another.
The reason it's done the way it's done has to do with order of operations. If you ignore order of operations, you can get infinite experience in a season. Happily, when ArM5 was originally created they paid attention to order of operations, using wording to distinguish things.
I think he basic idea is to try to avoid loops, where some source like correspondence gives you 1xp into abilty A, by some Virtue you can put half as many, rounded up, into ability B, but then you have an affinity that pushes that to 2, and a bonus etc. etc. ... and finally you get 1 more xp into ability A ... triggering the whole cycle again.