A R-table with attributes defined only on simple domains takes a less convoluted form -- a normal form -- devoid of nesting. If R-tables are in the preferred normal form i.e., components meaningful to applications (here, employee attributes) are simple domains in their own right and a true RDBMS enforces value atomicity -- first order logic is sufficient. This imposes some limitations on the expressive power of data languages, but they are declarative and PDI and simplicity are preserved. A true RDBMS enforces atomicity via a data language that does not allow applications to access attribute components not explicitly defined on their own domains.
Read it all (and comment there, please).
I have revised all three parts of the series on 1NF -- mainly refinements and clarifications.
- First Normal Form (1NF) in Theory and Practice, Part 1
- First Normal Form (1NF) in Theory and Practice, Part 2
- First Normal Form (1NF) in Theory and Practice, Part 3