OCS Block Subdivision Polygons Index

Official Protraction Diagrams (OPDs) are further subdivided into individual Outer Continental Shelf (OCS) blocks which are available as a separate layer. Some OCS blocks also contain other boundary information and are known as Supplemental Official Block Diagrams (SOBDs). The OPDs and SOBDs serve as the legal definition for BOEM offshore boundary coordinates and area descriptions. The SOBD maps can be accessed by clicking on the link in the Supplemental Official Block Diagram field of the attribute table. Further information on the history of the development of OPDs can be found in OCS Report MMS 99-0006: Boundary Development on the Outer Continental Shelf. These data were created in the applicable NAD83 UTM projection and re-projected to WGS84 Geographic. Because GIS projection and topology functions can change or generalize coordinates, these GIS files are NOT an OFFICIAL record for the exact boundaries. These files are to be used for Cartographic purposes only. These data should not be used to calculate area.官方延展图（Official Protraction Diagrams，简称OPDs）可进一步细分为独立的外大陆架（Outer Continental Shelf，简称OCS）区块，此类区块可作为单独图层获取。部分OCS区块还包含其他边界信息，这类区块被称为补充官方区块图（Supplemental Official Block Diagrams，简称SOBDs）。OPDs与SOBDs是美国海洋能源管理局（Bureau of Ocean Energy Management，简称BOEM）离岸边界坐标及区域描述的法定依据。可通过点击属性表中补充官方区块图字段的链接，获取SOBD地图。有关OPDs开发历史的更多信息，可参阅OCS报告MMS 99-0006《外大陆架边界开发》。本数据集采用适配的北美1983大地基准通用横轴墨卡托（NAD83 UTM）投影创建，并被重投影至世界大地测量系统1984地理坐标系（WGS84 Geographic）。由于GIS投影与拓扑功能可能会改变或简化坐标，因此这些GIS文件并非精确边界的官方备案文件。此类文件仅可用于制图用途。本数据集不得用于面积计算。