> ## Documentation Index
> Fetch the complete documentation index at: https://docs.variable.global/llms.txt
> Use this file to discover all available pages before exploring further.

# Models & inputs

`Model`s have many `Input`s. The source of an `Input` can be:

1. a `Material` that is made in-house or sourced from a `Supplier`
2. a `Processing` activity
3. a `Transportation` activity
4. a `Use Stage` calculation

<Info>
  [Model API documentation <Icon icon="square-arrow-up-right" iconType="light" />](/api-reference/v1/model)
</Info>

### Attributes

| Attribute       | Type          | Description                                                                                                                                                                                                                                    | Example                              |
| :-------------- | :------------ | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :----------------------------------- |
| uuid            | string        | The unique identifier                                                                                                                                                                                                                          | 123e4567-e89b-12d3-a456-426614174000 |
| name            | string        | The name of the input                                                                                                                                                                                                                          | Steel Handle                         |
| quantity        | number        | The amount of the input                                                                                                                                                                                                                        | 100                                  |
| unit            | Unit          | The unit of measure                                                                                                                                                                                                                            | kg                                   |
| order           | number        | The order of the input                                                                                                                                                                                                                         | 1                                    |
| material        | Material      | The material for the input                                                                                                                                                                                                                     | `{ uuid: "...", name: "Steel" }`     |
| recycledPercent | number        | Recycled content of this input as a percentage (0–100), inherited from its source product — the source's modeled recycled content when available, otherwise its declared value, or 0 when there is no source product or the source has neither | 30                                   |
| lifecycleStage  | LCA\_Category | The stage of the life-cycle the input is in                                                                                                                                                                                                    | `{ code: "A1", name: "Materials" }`  |
| CO2e            | decimal       | The CO<sub>2</sub>e value of the input                                                                                                                                                                                                         | 1234.5678                            |
| created         | date          | The date the input was created                                                                                                                                                                                                                 | 2021-01-01T00:00:00.000Z             |
| updated         | date          | The date the input was last updated                                                                                                                                                                                                            | 2021-01-22T00:00:00.000Z             |

`Input`s are categorized into Life-cycle assessment (LCA) categories.

### Diagram

```mermaid theme={"system"}
erDiagram
    Product ||--o{ Model : "has"
    Model ||--o{ Input : "has"
    Input ||--o| Processing : "processed by"
    Input ||--o| Transportation : "distributed by"
    Input ||--o| Material : "using source"
    Input ||--o| "Use Stage" : "has"

    Input {
        quantity number
        unit Unit
        CO2e decimal
        lifecycleStage LCA_Category
    }
```