Interesting Destination

I use the train a lot. Everyday I use the train to commute to my work. And although I know the train schedule by heart, I often glance at the electronic information boards.

A while ago I noticed a peculiar destination on the board. Below are pictures of the board and a close up. I never heard of a city called: "mmlh".

I keep wondering: How can a mistake like this be made? And for how long did it go unnoticed?