[en] This publication is an updated version of the Second Edition of the Explanatory Material for the IAEA Regulations for the Safe Transport of Radioactive Material (1985 Edition) and replaces all previous versions of Safety Series No. 7. This publication includes the changes to Safety Series No. 7 contained in the Regulations for the Safe Transport of Radioactive Material, 1985 Edition, Supplement 1988, as well as modifications adopted by the Review Panel that was convened in Vienna, 10-14 July 1989. For the convenience of the user, the old Safety Series style adopted in the original publication has been retained, although the old style has now been superseded by a new one, affecting the structure, the format and the cover of the Safety Series. It should be noted, however, that future editions will be published in the new style.