These Regulations amend the principal Regulations of 1994 by introducing revised criteria and guidelines for the classification of genetically modified micro-organisms for contained use purposes. "Contained use" means any operation in which organisms are genetically modified or in which such genetically modified organisms are cultured, stored, used, transported, destroyed or disposed of and for which physical barriers, or a combination of physical barriers, together with chemical and/or biological barriers, are used to limit their contact with the general population and the environment.