> 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="/files/Y5YvVMfExmQ10fKxug8X" alt=""><figcaption></figcaption></figure>