The SILL About page translated explains the list :

https://code.gouv.fr/sill/readme

Why this catalog?

The socle interministériel de logiciels libres (SILL) is the reference catalog of open-source software recommended by the French government for use throughout the administration.

This catalog helps administrations find their way around the open-source software they are encouraged to use, in line with Article 16 of the French Law for a Digital Republic

Or go to Spain or Germany, or Italy. They all have high speed trains (300-320 km/h commercial). , Spain has the largest high-speed network in Europe.