Introduction This draft standard is based on European discussions in which the UK took an active part. Your comments on this draft are welcome and will assist in the preparation of the consequent British Standard. Comment is particularly welcome on national legislative or similar deviations that may be necessary. Even if this draft standard is not approved by the UK@ if it receives the necessary support in Europe@ the UK will be obliged to publish the official English Language text unchanged as a British Standard and to withdraw any conflicting standard.