In what time standard do digital tachographs record ALL internal data and timestamps, and how does a driver in Austria calculate Central European Time (CET / MEZ) and Central European Summer Time (CEST / MESZ) from a raw tachograph UTC printout?

1. All data is strictly recorded in UTC (Coordinated Universal Time); local Austrian winter time (CET) is UTC + 1 hour, and local Austrian summer daylight saving time (CEST) is UTC + 2 hours
2. Data is recorded in local Austrian time; UTC is calculated by subtracting 3 hours
3. Data is recorded in Greenwich Mean Time minus 5 hours
4. Each tachograph automatically converts internal stored records to the driver's home time zone