OH-stations using suffix /S or /SA indicate stations using old military equipment during special commemorative events, usually 4th June or 6th December each year, but these suffices can be on air other times as well.
Current rules state that equipment must be at least 40 years old to be used with /S and have actually been
"/S" stands for the Finnish word "sotilaskalusto" which means "military equipment".
"/SA" stands for "sotilaskalusto aktiivikaytossa" which means "military equipment actually used in war".
used in Finnish military operations during WW2 to be used with /SA.
Thanks to OH6NT for the above information.
Club Log maps callsigns with the /S suffix by means of a software rule and maps callsigns with the /SA suffix by means of callsign exceptions..