diff --git a/esmvalcore/config/extra_facets/native6-mappings.yml b/esmvalcore/config/extra_facets/native6-era5.yml
similarity index 93%
rename from esmvalcore/config/extra_facets/native6-mappings.yml
rename to esmvalcore/config/extra_facets/native6-era5.yml
index 0ebfe5939e..d15f4aab79 100644
--- a/esmvalcore/config/extra_facets/native6-mappings.yml
+++ b/esmvalcore/config/extra_facets/native6-era5.yml
@@ -1,4 +1,8 @@
-# Extra facets for native6 data
+# Extra facets for native6 ERA5 data in GRIB format
+#
+# See
+# https://docs.dkrz.de/doc/dataservices/finding_and_accessing_data/era_data/index.html#file-and-directory-names
+# for details on these facets.
 
 # Notes:
 # - All facets can also be specified in the recipes. The values given here are