Square Points

Squares are calculated by the outer extents of the record or tax lots within a defined area (typically a city block). There are roughly 4896 active squares. A Square is similar to a city block. Squares were numbered starting at 1 and are currently in the 6000 series. Not all squares are active. A common cause of squares becoming inactive has been through street closing and combining squares. When the squares are combined usually the lower square number is killed and the higher square number is used for the combined square. For example if squares 1 and 2 are combined, square 1 is killed and the combination becomes square 2. Spatial locations: Each Square is an Island, alone unto itself. There is not now, and has never been, any citywide Survey Coordinate System in D.C. Most squares are unrelated to other Squares by “Measured.” They are related by Record. Street width is approximate. You cannot rely on the published official street widths to set up property lines or determine right-of-way. There is digital scan information available from DDOT regarding Right-of-Way. Some Squares are divided by streets. That is, the same Square continues on the other side of the street. Since there is no citywide Survey Coordinate System, squares were placed in their approximate location. This process is known as “best fit”.本数据集的地块单元（Square）以划定区域（通常为街区）内的记录地块或税籍地块（tax lots）的外边界进行划定，当前共有约4896个有效地块单元。地块单元的概念与街区近似，其编号初始为1，当前已更新至6000序列，且并非所有地块单元均处于激活状态。导致地块单元失效的常见原因为道路封闭与地块单元合并：合并地块单元时，通常保留编号较大的地块单元，注销编号较小的地块单元。例如将地块单元1与2合并时，将注销地块单元1，合并后的地块单元沿用编号2。 空间定位说明：每个地块单元均为独立地理单元，彼此互不关联。华盛顿哥伦比亚特区（D.C.）目前未曾、也从未建立过全市统一的测量坐标系（Survey Coordinate System），因此多数地块单元之间不存在实测关联，仅通过行政记录产生关联。 道路宽度仅为近似值，不得仅凭官方公布的道路宽度划定产权界址或认定道路用地权（right-of-way）。相关道路用地权的数字化扫描档案可从华盛顿特区交通局（DDOT）获取。 部分地块单元会被道路分隔，即同一地块单元会跨越道路延伸至另一侧。由于缺乏全市统一的测量坐标系，地块单元的位置通过「最佳拟合（best fit）」流程确定为近似坐标。