> For the complete documentation index, see [llms.txt](https://docs.tesenso.com/tesenso-iot-cloud/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tesenso.com/tesenso-iot-cloud/device-type-library/relation-type-keys.md).

# relation Type keys

We highly recommend to use whenever possible **Contains** as relation Type.

<figure><img src="https://111806075-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-Mg4otljWU9FsHKYhTsW%2Fuploads%2FXp0YB1MRELFbjRiwrSeQ%2Fimage.png?alt=media&amp;token=f601ae44-5373-48c7-82d7-da1027c762f9" alt=""><figcaption></figcaption></figure>