Periodic Table organizes many WoW items and spells into sets. Like most Ace addons it's focus is efficiency. PT is a LibStub library for managing these sets (ex: Misc.Spell.Mount, Consumable.Food.Edible.Cheese, Misc.Minipet, ClassSpell) for other addons.
If you are looking for a tooltip display addon check out Mendeleev, which you can find on Curse or WoWI.
Item sets are stored as a comma-delimited strings and parsed out into a table only if requested. This speeds up load time and ensures that memory is only used for sets that are actively used.
If you are interested in using PT with your mod feel free to read the source code (there's not a lot). The comments will tell you everything you need to know.
Modules
PeriodicTable's "modules" are simply sets of sets. Particular mods can link the exact sets they need.
- ClassSpell - Spells for all classes with subsets for each tree.
- Consumable - Foods, Potions, Elixirs, Buffing items including type (fruit, meat, etc), quality (inedible, buff) and HP-recovery info.
- CurrencyItems - Items purchasable with various currencies.
- Gear - Socketed gear, Trinkets, Vendor Badge gear
- GearSet - Set Gear. Tier, Reputation, PvP, etc.
- InstanceLoot - Loot tables for instances and the bosses in those instances (only higher-level instances currently)
- InstanceLootHeroic - Loot tables for heroic instances
- Misc - Random stuff like Currency, Containers, Mounts, etc.
- Reputation - Rewards and Turnins for factions
- Tradeskill : Profession recipes
- TradeskillLevels : Profession recipes with level requirements
- TradeskillResultMats : Some kinda mats required sets for the recipes it looks like
