You can draw dimensions in both Model space and Paper space. However, if the geometry you are dimensioning is in Model space, it is best to draw dimensions in Model space because AutoCAD places the definition points in the space where the geometry is drawn.
可以在图纸空间和模型空间中绘制标注。但是，如果要标注的几何图形位于模型空间中，则最好在模型空间中绘制标注，因为 AutoCAD 会将定义点放在绘制几何图形的空间中。
If you draw a dimension in Paper space that describes geometry in your model, the Paper space dimension does not change when you use editing commands or change the magnification of the display in the Model space viewport. The location of the Paper space dimensions also stays the same when you change a view from Paper space to Model space.
如果用户在图纸空间中绘制标注，而此图纸空间用于描述模型空间中的几何图形，则当用户使用编辑命令或者修改模型空间视口中显示的放大比例时，图纸空间标注并不会改变。当用户将视图从图纸空间切换到模型空间时，图纸空间标注仍会停留在原处。
If you are dimensioning in Paper space and the global scale factor for linear dimensioning (the DIMLFAC system variable) is set at less than 0, the distance measured is multiplied by the absolute value of DIMLFAC. If you are dimensioning in Model space, the value of 1.0 is used even if DIMLFAC is less than 0. AutoCAD computes a value for DIMLFAC if you change the variable at the Dim prompt and select the Viewport option. AutoCAD calculates the scaling of Model space to Paper space and assigns the negative of this value to DIMLFAC.
如果正在图纸空间进行标注，并且线性标注的全局比例因子（DIMLFAC 系统变量）已设置为小于 0（零），则测量的距离将被乘以 DIMLFAC 的绝对值。如果正在模型空间进行标注，则即使 DIMLFAC 小于 0（零），仍将使用值 1.0。如果在“标注”提示下更改变量并选择“视口”选项，则 AutoCAD 将计算 DIMLFAC 的值。AutoCAD 将计算从模型空间到图纸空间的缩放比例，并将该值的负值指定给 DIMLFAC。
