Cairn Documentation
Nodes & Properties
Nodes are the building blocks of every model. Each node represents a piece of your system at some level of abstraction.
What a Node Contains
- Name: A short identifier ("Power Subsystem", "Battery Pack")
- Type: system, subsystem, assembly, part, or external
- Description: Plain-language explanation of what this node is and does
- Parent: Which node contains this one (except the root)
- Properties: Engineering parameters like mass, power, cost
Editing Nodes
Every field on a node is editable directly. Open the Inspector panel and click a field — the title, description, type, or any property — and type. The change commits immediately; no review step.
Right-click a node in the tree or on the Architecture canvas for contextual operations: Rename, Add child, Decompose with AI, or Delete. The Architecture canvas adds Connect to… for wiring up interfaces, since the canvas is where you can see both endpoints. Deletes show a cascade preview of every requirement, interface, state, and trace link that would go with the node, so you can see the blast radius before you confirm.
The Properties Catalog
Properties are key-value pairs with engineering semantics:
- Key: Identifier (e.g., "mass", "power_nominal")
- Value: Numeric or text value
- Unit: From the project's unit catalog (kg, W, mm, etc.)
- Category: Grouping (physical, electrical, thermal, etc.)
- Source: Where this value came from (estimate, datasheet, test, derived)
| Property | Unit | Category | Typical Use |
|---|---|---|---|
| mass | kg | physical | Weight budgets |
| power_nominal | W | electrical | Power budgets |
| power_peak | W | electrical | Worst-case analysis |
| cost | USD | economic | Cost rollups |
| mtbf | hours | reliability | Reliability analysis |
| operating_temp_min | °C | thermal | Environmental limits |
| operating_temp_max | °C | thermal | Environmental limits |
Budget Rollups
Some properties roll up automatically from children to parents. A subsystem's mass is the sum of its parts' masses. The Overview lens shows budget bars comparing allocated vs. actual values.
AI Property Suggestions
The Properties panel includes an AI suggestion button that proposes domain-appropriate properties based on the node's name, type, and description. Accept individually or all at once.