We're all familiar with magical traditions (more or less)

Buddhist Tradition
Combat: Air
Detection: Guidance
Health: Earth
Illusion: Fire
Manipulation: Water
Drain: Willpower + Intuition

What I cant seem to figure out is what RAW calls "magical associations" and expands on that no further. I understand that the list of spirits is the spirits that tradition can summon, but what are the different spell categories for? Do those denote what category of spell you can give to that particular spirit?

Can anyone more familiar with magic enlighten me?

The categories are what kinds of spirits can be used to assist with what kinds of spells. From the tradition above, look like you'll want to summon an earth spirit to get help learning a health spell. I'm pretty sure thesame goesfor sustaining etc.

That seems remarkably narrow

If you want more bredth, a Spirit of Man can cast (and then sustain, if a Permanent or Sustained spell) any spells its summoner grants it via the Innate Spell spirit power: one spell per three points of spirit Force (round down). The spirit does have to resist drain, though (unlike other spirit powers).

This is how it's been since First Edition... The school of magic and the spirit type are directly linked. You can only use one type of spirit to aid it's associated spell category.

-D

By assist, how do you mean? As in you can only load them with that kind of spell?

Bound spirits can do the following as a service, but only for their magical "school", as determined by your Tradition:
* Aid Sorcery (add their Force to Spellcasting, Ritual Spellcasting or Counterspelling dice pool)
* Aid study (add their Force to your learning dice pool)
* Sustain a spell for the spirit's Force # of combat turns (relieving the mage of the burden)

The only Spirit type that actually casts spells is the Spirit of Man. The others can only Aid in the Associated Spell category that they pertain to. See Ascalaphus' post above.

What about spirits that are not bound, as in spirits that you just summon on the battlefield?

They can't do any of those things. Those are services that only Bound spirits can deliver.