"The system of nomenclature used in identifying the parts of the alternative corridors investigated is graphically explained on Map 2. Although the term ""Corridor"" is used for systematic purposes it must be noted that in Corridor D there are great numbers of corridors included. The net-like character of the alternatives in the northern regions made it more practical to break the net into Segments and, where convenient, to break the Segments into Sections. The location of Corridors and segments is graphically indicated on Map 2. The data in the Appendix are arranged alphabetically by Corridor letter and numerically by Segment within each Corridor. Where the Segment has been subdivided into sections , these are arranged alphabetically. These divisions of corridors may be combined in various sequences as necessary to complete a desired corridor across an area."