# Read MOI Volume

Get file references from a Catalog volume or selected files for parsing, import, and other file-processing nodes.

This node selects a set of files; it does not parse their contents into document text.

## Choose a source

| Setting | Description |
| --- | --- |
| Data source | Select a Catalog volume or file source; runtime input: `source_ref` |
| File type | Optional extension filter for a volume; leave empty to read all its files |

Selecting specific files and selecting an entire volume produce different input scopes. Check the count and file types before connecting parsing or import nodes.

## Choose the downstream output

| Output | Use |
| --- | --- |
| `sources` | Document, image, audio, or video parsing |
| `files` | File metadata array containing `file_id`, `name`, and `file_name`, for nodes such as Information Extraction |
| `file_ids` | File ID array, for inputs such as file import |
| `count` | Number of selected files or resources |
| `resource` | Resolved source resource reference |

These fields describe the same file set. Choose the one expected by the next node. If it accepts only one file, extract the corresponding `file_id`.

## Example: process PDFs in a volume

Flow: Read MOI Volume → General Document Parsing.

Select a source volume, filter by the PDF extension, and bind `sources` to General Document Parsing. Check the file count before reviewing parsing results.

## Related pages

- [Variables and data flow](../../variables-and-data.md)
- [Run and debug](../../run-debug.md)