Icons within this folder are reproduced from the European Railways Association ETCS DMI documentation at
[ETCS 4.0](https://www.era.europa.eu/system/files/2023-12/index006_-_ERA_ERTMS_015560_v400.zip)
and
[ETCS 3.6](https://www.era.europa.eu/system/files/2023-01/sos3_index006_-_era_ertms_015560_v360.zip)
accessed January 2024, as per their Copyright notice at 
[ERA Copyright Notice](https://www.era.europa.eu/content/disclaimer-and-copyright-notice)