Great Britain. Directorate of Overseas Surveys. Great Britain. Ministry of Overseas Development (Directorate of Overseas Surveys) North Decimal Degree 18.000000. South Decimal Degree 17.7500. East Decimal Degree -88.0000. West Decimal Degree -88.2500. Standard map series designation: series E755 (D.O.S. 4499). Transverse Mercator projection. Grid: U.T.M. zone 16. Relief shown by 20 m. contour interval and spot heights.