Notation and Diagrams¶
Systems representing supply chains are beste understood when visualized using a well-defined diagrammatic notation. The greengraph package uses a notation formalized by Weinold in 2025. It defines the following elements, describing nodes and edges of the graph diagram:
| Image | Type | Description | Notes |
|---|---|---|---|
 |
node | sector \(A\) | Squares represent sectors of the input-output (="sectoral system"). They are labeled using capital letters. |
 |
node | process \(1\) | Circles represent production processes of the life-cycle inventory (="process system"). They are labeled using numbers. |
 |
node | burden \(\alpha\) | Diamonds represent environmental burdens or satellite extensions. They are labeled using lowercase Greek letters. |
 |
edge | process flow \(a^P_{21}\) | Dashed lines represent flow information derived from the process system. |
 |
edge | process flow \(a^S_{BA}\) | Solid lines represent flow information derived from the sectoral system. |
 |
edge | upstream flow \(c^U_{B1}\) | Red-colored lines represent flow from sectors to processes. For historical reasons, this is named upstream flow. |
 |
edge | downstream flow \(c^D_{2A}\) | Blue-colored lines represent flow from processes to sectors. For historical reasons, this is named downstream flow. |
Using this notation, the matrices underlying a simple example system can easily be reproduced. For example, the example system: