> For the complete documentation index, see [llms.txt](https://docs.sign.global/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sign.global/for-builders/advanced-topics/schema-hooks/tutorial-checking-attestation-data.md).

# Tutorial: Checking Attestation Data

In this tutorial, we will create a schema hook that checks an attestation's `data` variable. A threshold value must be met for the attestation to be created. When you are ready to begin, please navigate to the next page.