Standards families
SysML block definition diagram
Blocks, their properties (parts, values, references) and the relationships between blocks: composition, generalisation, association.
sysml.bdd@2New DDN source
Why use it?
The BDD is the system's nouns and their structure — every other SysML view hangs off these definitions.
When it helps
Systems architecture decomposition, from vehicle-scale down to a single assembly.
How to read it
- Blocks are boxes with compartments; filled-diamond lines are composition (owned parts).
- Read multiplicities on part ends — they bound the internal block diagram.
What you need
- The blocks
- Their properties
- The structural relationships
Things to check
- Do not confuse composition (part-of, one owner) with reference (used-by).
- A part with no multiplicity is an under-specified IBD waiting to happen.
Scope of this diagram
Declared structure with SysML well-formedness validation; no analysis or simulation is implied.
Work with the converted example
- Open the viewer and select
bdd. 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.