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

# SDK and model versions

> How core SDK releases and model file versions fit together.

The core SDK and model files are versioned together. Model file versions change as part of an SDK release, not independently for an unchanged SDK version.

| Version                       | What it identifies                                                       |
| :---------------------------- | :----------------------------------------------------------------------- |
| **Core SDK version**          | The runtime that loads and runs models, such as `0.24.0`                 |
| **Model file format version** | The file format that the core SDK accepts, such as `7` for core `0.24.0` |

Several SDK releases can support the same model file format. A new SDK release does not always require new model files.

Language packages have their own version numbers. For example, Python `3.2.0` uses core SDK `0.24.0`. Use the [compatibility matrix](/reference/sdk/compatibility-matrix) to match your package to its core SDK and model file format. A product version in a model ID, such as `2.2` in `quail-vf-2.2-l-16khz`, is separate from the file format number.

## Upgrade the SDK and models together

Check the [changelog](/changelog) for changes in your target SDK release. If it requires a new model file format, download the models again using the updated SDK's download helper, which selects a compatible file. See [model loading](/reference/sdk/models#loading-and-reusing-models).

Keep the previous SDK and model files together until you have tested the updated combination in your application.