diff --git a/guide/sections/part2/global-services.adoc b/guide/sections/part2/global-services.adoc
index 3dd9bbe..82d4836 100644
--- a/guide/sections/part2/global-services.adoc
+++ b/guide/sections/part2/global-services.adoc
@@ -148,6 +148,7 @@ In WIS2, Global Caches provide access to WMO core data for data consumers. This
 * If the Global Cache is not able to download the data, the metric ``wmo_wis2_gc_downloaded_error_total`` will be increased by 1.
 * A Global Cache shall provide the metric defined in this Guide at an HTTP endpoint.
 * A Global Cache should make sure that data are downloaded in parallel and that downloads are not blocking each other.
+* A Global Cache will implement https://datatracker.ietf.org/doc/html/rfc2616#section-10[Status Code Definitions] as defined by the https://datatracker.ietf.org/doc/html/rfc2616[HTTP specification].
 
 * The metric ``wmo_wis2_gc_dataserver_status_flag`` will reflect the status of the connection to the download endpoint of the centre. Its value will be 1 when the endpoint is up and 0 otherwise.
 * The metric ``wmo_wis2_gc_last_metadata_timestamp_seconds`` will reflect the datetime (as a timestamp, the number of seconds since the UNIX epoch) of the last metadata resource processed by a given centre.