Data structures and meaning
Nested fields — domains and representations
Fields nested inside elements: domains and physical representations as collapsible rows, with identities that survive the collapse.
ddn@1New DDN source
Why use it?
Logical-to-physical detail belongs on the element, and collapsing must never lose the endpoint a relation lands on.
When it helps
Domain modelling where each attribute carries a type, a domain and a physical representation.
How to read it
- Rows inside an element are its nested fields; indentation is the nesting.
- The collapsed variant hides rows — relation endpoints still resolve to the same identities.
What you need
- The elements
- The nested field rows
- The relations into nested endpoints
Things to check
- Do not model a field as a separate box when it belongs to its element.
- Collapsing is a view choice — if an endpoint vanishes, that is a defect, not a feature.
Scope of this diagram
Declared nesting with identity preservation validated across collapse; type checking beyond declaration is out of scope.
Work with the converted example
- Open the viewer and select
detailed. Inspect the rendered view and its source. - Open the designer. Keep the selected profile and inspect its legal palette and property controls.
- Change one displayed title or an appropriate data value. Apply the edit and check the resulting diagram.
- Run the verifier and review its diagnostics before moving complete content into review.
- Download your edited DDN source to retain the change.
The example uses the indentation-based ddn-next-1 dialect. The language guide explains reusable definitions, dotted data rows and explicit property blocks.