# Layer L3  --  Feature engineering

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- Layer ID: `l3`
- Category: `construction`
- Sub-layers: 4
- Axes: 1
- Options across axes: 52

## Sub-layers

| Sub-layer | Name | Gate | Axes |
|---|---|---|---|
| `L3_A_target_construction` | Target construction | always | _no axis options at this sub-layer; see operational ops in `core/ops/`._ |
| `L3_B_feature_pipelines` | Feature pipelines | always | _no axis options at this sub-layer; see operational ops in `core/ops/`._ |
| `L3_C_pipeline_combine` | Pipeline combine | always | _no axis options at this sub-layer; see operational ops in `core/ops/`._ |
| `L3_D_feature_selection` | Feature selection | always | _no axis options at this sub-layer; see operational ops in `core/ops/`._ |

```{toctree}
:hidden:
:maxdepth: 1

axes/op
```