@kitten The improved local railway network around Brussels was planned under the RER brand, but because Belgium is bilingual in the most absurd way, they obviously couldn't use réseau express régional in Dutch without causing a political scandal - so they just translated that to Dutch and it became Gewestelijk ExpresNet, RER/GEN. SNCB/NMBS realized that that's silly, and introduced the brand instead, which is communicated as "train S"/"S trein"/"S-Zug"/"S train" in French, Dutch, German, and English
1