docs(#246): correct the diagram edge-weight rule - #247
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Line weight encodes cardinality, and it is binary: thick = 1:1 (the foreign key
is the child's entire primary key); thin = multi-valued (the child adds
primary-key attributes of its own, newly declared or inherited from another FK).
The old table inverted this ('thick = Master-Part'); a master->part edge is
actually thin, since a part adds a key attribute. Note the rule is rename-safe (a
renamed FK can still be 1:1) and is the same fact as the underline rule viewed
from the edge. Pairs with datajoint-python #1532.
This was referenced Aug 10, 2026
fix(#1532): diagram edge weight encodes cardinality, not master-part
datajoint/datajoint-python#1533
Merged
…tion Fix stale rows in the Table Tiers table (Lookup and Part are now rectangles, not 'plain text'; Part is smaller/muted white), and update the make_mermaid() output example to the current palette and cardinality linkStyle. Companion to the edge-weight rule correction in this PR.
MilagrosMarin
approved these changes
Aug 13, 2026
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Fixes the incorrect edge-weight rule in
reference/specs/diagram.md§ Visual Encoding. Documentation companion to datajoint/datajoint-python#1532 (the generator correctness fix).The error
The old table stated the weight rule inverted:
|
Thick line|Master-Part relationship||
Thin line|Multi-valued foreign key|Line weight encodes cardinality, and it is binary:
Master-part is not a weight: a part almost always adds a key attribute, so a master→part edge is thin. Attributing thick to master-part inverted the encoding on exactly the edges a reader checks first.
Also documented
Not in this PR
The modernized diagram style (tier palette, entity groups, direction, renamed-edge color) documentation lands with the generator restyle (#1532 parts 2–4), so the spec and renderer stay in step.