itemFamily is a bitfield (a number usable with bitlib)
- 0 = Unspecified (for bags it means any item, for items it means no special bag type)
- 1 = Quiver
- 2 = Ammo Pouch
- 4 = Soul Bag
- 8 = Leatherworking Bag
- 16 = Inscription Bag
- 32 = Herb Bag
- 64 = Enchanting Bag
- 128 = Engineering Bag
- 256 = Keyring
- 512 = Gem Bag
- 1024 = Mining Bag
- 2048 = Unknown
- 4096 = Vanity Pets
To date (patch 3.2), no bags are flagged as combination of these bits, but it is entirely possible that such bags will be added in the future.
Note that GetItemFamily() on e.g. an unequipped herbalism bag (placed inside your bags!) will still return e.g. "32". But that does NOT mean it can be placed inside an equipped herbalism bag! The best way to test if an object is a bag is e.g. select(9,GetItemInfo(itemLink))=="INVTYPE_BAG"