附在文件上我还是喜欢用 vlax-ldata-xxx
xdata扩展数据 就是附在一个图元上的了的数据了,
Extended data (xdata) is created by AutoLISP or ObjectARX applications. If an entity contains extended data, it follows the entity's normal definition data. The group codes 1000 through 1071 describe extended data. The following is an example of an entity containing extended data in DXF format.