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+# User's guide
+
+```{important}
+This guide is in the making.
+```
+
+## NVD datasets
+
+Our tool matches certificates to their possible CVEs using datasets downloaded from [National Vulnerability Database (NVD)](https://nvd.nist.gov). If you're fully processing the `CCDataset` or `FIPSDataset` by yourself, you must somehow obtain the NVD datasets.
+
+Our tool can seamlessly download the required NVD datasets when needed. We support two download mechanisms:
+
+1. Fetching datasets with the [NVD API](https://nvd.nist.gov/developers/start-here) (preferred way).
+1. Fetching snapshots from seccerts.org.
+
+The following two keys control the behaviour:
+
+```yaml
+preferred_source_nvd_datasets: "api" # set to "sec-certs" to fetch them from seccerts.org
+nvd_api_key: null # or the actual key value
+```
+
+If you aim to fetch the sources from NVD, we advise you to get an [NVD API key](https://nvd.nist.gov/developers/request-an-api-key) and set the `nvd_api_key` setting accordingly. The download from NVD will work even without API key, it will just be slow. No API key is needed when `preferred_source_nvd_datasets: "sec-certs"`