Sometimes a train is late, but traffic controllers can not say for how long.

If this is the case, timetable rows now have a unknownDelay-property set to value true

More (in Finnish): https://www.liikennevirasto.fi/-/juna-myohassa-eika-arviota-lahtoajasta-asemien-nayttotaulut-kertovat-taman-pian-uudella-tavalla