# Append Processing Data

## Summary
Append signal data from IoSources into a processing DataBundle.

## Metadata
- **Module ID:** AppendProcessingData
- **Module path:** /home/runner/work/MoDaCor/MoDaCor/src/modacor/modules/base_modules/append_processing_data.py
- **Module version:** 20251030.3
- **Keywords:** append, processing, data, signal

## Required data keys
- _None_

## Modifies
- _None_

## Required arguments
- processing_key
- signal_location
- rank_of_data

## Default configuration
```json
{
  "databundle_output_key": "signal",
  "processing_key": "",
  "rank_of_data": 2,
  "signal_location": "",
  "uncertainties_sources": {},
  "units_location": null,
  "units_override": null
}
```

## Argument specification
| Argument | Type | Required | Default | Description |
|---|---|---|---|---|
| `databundle_output_key` | str | No | signal | BaseData key inside the DataBundle. |
| `processing_key` | str | Yes |  | ProcessingData key to create or update. |
| `rank_of_data` | int or str | Yes | 2 | BaseData rank as int or IoSources metadata reference. |
| `signal_location` | str | Yes |  | IoSources reference '<io_source_id>::<dataset_path>'. |
| `uncertainties_sources` | dict | No | {} | Mapping of uncertainty name to IoSources reference. |
| `units_location` | str or NoneType | No | - | Optional IoSources reference for units metadata. |
| `units_override` | str or NoneType | No | - | Optional unit string that overrides loaded units. |

## Notes
This step reads from existing IoSources and creates or updates a named DataBundle with a BaseData entry (default 'signal') for use in the processing pipeline.