It is listed in Guinness World Records as the shortest subway system in the world, being the second smallest track network (after the Tünel in Istanbul,) but being the smallest "system" by virtue of being the only urban rail network in the city.
TUNEL assay (Terminal deoxynucleotidyl transferase mediated dUTP Nick End Labeling assay), in genetics, a method for detecting DNA fragmentation
Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) is a method for detecting DNA fragmentation by labeling the terminal end of nucleic acids.