ItemWithQualityID - Runtime Docs

ItemWithQualityID :: union

An item prototype with optional quality specification. Can be specified in one of four ways.

LuaItemStack	The item stack. Both prototype and quality of the item stack will be used.
LuaItemPrototype	The item prototype. Normal quality will be used.
string	The prototype name. Normal quality will be used.
ItemIDAndQualityIDPair	A table of item prototype and quality.