It also considered that account should be taken of the order of precedence of the tanks and that an indication should be given of groups of substances which could also be carried in the tank in question and required a lower level of performance . Lastly , it considered that reference should be made to the special construction ( TC ) and equipment ( TE ) requirements in subsections 6.7.3.1 and 6.7.3.2 ( document —/1998/39 ) .