> 1NF is about eliminating nested relations. Absolutely agree, this is the definition of 1NF. So if you have a relation which has an attribute which has a doma

> 1NF is about eliminating nested relations. Absolutely agree, this is the definition of 1NF. So if you have a relation which has an attribute which has a domain which itself include relations - then you have a 1NF violation. "From the perspective of the database" is perhaps too vague (although Codd uses almost the same phrasing), the question is if the value is atomic with regard to the relational operators (project, join etc.). Can you INSERT a tuple into a value? Then the value is a relation. I get that at a certain abstraction level a comma separated string value could be considered a list or a relation. But then it would be at a different abstraction level than the one where the containing table is a relation. Because you can select rows and column from this outer relation using the relational operators, but you cant do the same for a relation encoded into a string value.