A UL approval, Type "LP" tag means that the forklift truck was propane powered when it left the factory. I have seen many instances where a forklift was originally type "G", which is gasoline powered, and then converted to propane. In the US, if OSHA where to check a truck that had a type "G" tag on it but was converted to propane they could make you have have UL approve the conversion which is incredibly expensive.
Do a search on GOOGLE, Type in "UNDERWRITERS LABORATORY" and check out the sites. They will explain.