Often all the locations in a data area have the same scope in the source program. 一个数据区中所有单位在源程序中常常有相同的定义域。
A backup that contains only the data extents that were modified since the most recent partial backup of the same set of filegroups. 这种备份仅包含自同一组文件组的最新部分备份以来发生了修改的数据区。
