Attribute values (tags) for items. Note that this is different from ItemRequest.ItemAttributes -
the values set here are "tags" for an item, such as color or clothes size. Tags are searchable by users and
may be added or removed from the system at any time.
- Terms, The TermValues (string/text based attribute values).
- Numbers, The NumberValues (numeric attribute values), used for numeric
attributes such as mileage, model year, and engine size.