The nationality mark TS has never actually been used although
it appears that it has been allocated officially.
After the second world war Triest was separated from Italy and divided
in two parts, the first part was occupied by British and American
forces, the second part by Yugoslavia.
In the British and American zones registrations were of an Italian
style, but black on white with the city crest on the plate.
In 1954 this part came back to Italy and resumed it's former
registrations.
The Yugoslavian zone used the letters STT and a three digit
serial number.
In 1946 this was changed to STT followed by a star and a
four digit serial number.
In 1954 this part came to Yugoslavia within Croatia.