This new text of Sophocles is the product of many years of close collaboration between the two editors. The evidence of the manuscript tradition has been carefully assessed, and the results of one important discovery have been exploited for the first time. It has also been possible to take account of many little known or forgotten conjectures. A number of other conjectures are correctly attributed for the first time, and in a few passages the editors have ventured to offer proposals of their own.