> ## Documentation Index > Fetch the complete documentation index at: https://openrouter.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # ExtractionAsset An image or PDF sent once and referenced by its key in the `assets` map. `data_base64` is the file in standard base64 with no `data:` prefix. PDF is read by document models only. ## Fields | Field | Type | Required | Description | | - | - | - | - | | `DataBase64` | `string` | ✔️ | N/A | | `Format` | [components.ExtractionAssetFormat](../../models/components/extractionassetformat.mdx) | ✔️ | N/A | | `Type` | [\*components.ExtractionAssetType](../../models/components/extractionassettype.mdx) | ➖ | N/A |