EarlyWarning alert not transmitted as EarlyWarning but as a Preliminary alert with negative Latency
The superevent S220915cl has corresponding EarlyWarning uploads. The first GCN is sent out negative latency but the Notice type is Preliminary and not Early Warning.
https://gracedb-playground.ligo.org/api/superevents/S220915cl/files/S220915cl-1-Preliminary.xml,0