Introduction This draft standard is based on national and international discussions. Your comments on this draft are invited and will assist in the preparation of the consequent standard. For international standards@ comments will be reviewed by the relevant UK national committee before sending the consensus UK vote and comments to the international committee@ which will then decide appropriate action. If the international standard is approved@ it is usual for the text to be published as a British Standard. For national standards@ comments will be reviewed by the relevant UK national committee and the resulting standards published as a British Standard.