They have no Lore requirement. Talent "Petty Magic" lets you learn any Petty Spell. The Horned Rat Companion states that only Skaven can learn Skaven Petty Spells. It is unclear if anyone can learn Petty spells of Slaanesh and Tzeentch, but "Adventure Seed: An unwelcome Talent" in Death on the Reik Companion p.98 suggest that they available for anyone with Petty Magic.
Subtypes:
- Petty Spell of Slaanesh (Power Behind the Throne Companion)
- Petty Spell of Tzeentch (Death on the Reik Companion)
- Skaven Petty Spell (The Horned Rat Companion)
Those spells are common to all Lores so every Arcane Magic spell belongs to all the Lores.
Subtypes:
- Chaos Arcane Spells are available only for Chaos Magic users
Ritual spells are regular lore spell just with different casting technique.
- Colour Magic
- Light (White, Hysh)
- Metal (Gold, Chamon)
- Life (Jade, Ghyran)
- Heavens (Blue, Azyr)
- Shadows (Grey, Ulgu)
- Death (Amethyst, Shyish)
- Fire (Red, Aqshy)
- Beasts (Amber, Ghur)
- Dark Magic (Black, Dhar)
- Daemonology
- Necromancy
- Witch Magic
- Hedgecraft
- Witchcraft
- Chaos Magic
- Nurgle
- Slaanesh
- Tzeentch
- High Magic (Qhaysh)
- General High Magic
- Slann High Magic
- The Great Maw (Gut Magic, Gastromancy) <- Ogres only
- Fimir Marsh Magic
- Waaagh!
- Little Waaagh!
- Big Waaagh!
- Skaven Magic
- Plague
- Stealth
- Ruin