Антверпен,

BN PCC Antwerpen (modernised)

№ 2121

—  маршрут 24

This tram had then been newly renovated, including new doors and a strip to open the doors. The blue diamond alerted passengers to this, namely that they therefore no longer had to rely on the driver to open the doors.
The system proved to be very impractical and was later replaced by a regular button. The blue diamond then disappeared again when all trams were equipped with self-service doors.