So, I think I have realised that there are “lists” and “Lists”.
I have a “list” of OBJECTS (Data Type) but in the DATA TAB a “List” refers to a “Lists of Things” where there is more than one example of the Thing for that Object.
So, “Title” type would be text only (no list) as there is only one Title per OBJECT. Similarly, Medium as an OBJECT can only have one medium (oil on canvas, watercolour, bronze).
However, I would choose “This type is a list of elements” where it is possible to have more than one. So, strangely, as it is the art world, and OBJECT can have more than one PRICE as it can be sold any times, from a gallery, then from a Auction House, then privately. Similarly with Literature, as there could be many books that mention the same OBJECT.
So where there is only ONE instance of a field for an OBJECT, no lists. Am I right? (Because, so far, I made my data fields all wrong!)