Minecraft wiki entry for Raw_JSON_text_format, associated text: The text component.
 nbt: The NBT path used for looking up NBT values from an entity, block entity, or storage. Requires one of  block,  entity, or  storage. Having more than one is allowed, but only one is used.[note 5]
 interpret: Optional, defaults to false. If true, the game attempts to parse the text of each NBT value as a raw JSON text component. Ignored if  nbt is not present.
 separator: Optional, defaults to {"text": ", "}. A raw JSON text component. Used as the separator between different tags, if the component selects multiple tags.
 block: A string specifying the coordinates of the block entity from which the NBT value is obtained. The coordinates can be absolute, relative, or local. Ignored if  nbt is not present.
 entity: A string specifying the target selector for the entity or entities from which the NBT value is obtained. Ignored if  nbt is not present.
 storage: A string specifying the namespaced ID of the command storage from which the NBT value is obtained. Ignored if  nbt is not present.