Your memory is serving you very ill. These various symbols were standardized in 1973. The one that you are searching for a name for is the standby symbol. St

Your memory is serving you very ill. These various symbols were standardized in 1973. The one that you are searching for a name for is the standby symbol. Standby buttons do not actually power computers off. (Circuitry that handles waking up from standby is, of course, still powered on.) https://www.iso.org/obp/ui#iec:grs:60417:5009 https://www.iso.org/obp/ui#iec:grs:60417:5009