Even though Power Dimensioning honors DIMLFAC, we do not recommend its use. This is because AutoCAD Mechanical toolset uses several scaling mechanisms that are not available in AutoCAD, which may not work well, especially if you use different values of DIMLFAC in different places in the drawing.
For example, scale areas, detail views, and annotation views allow model space to be divided into areas having different scales. Power Dimensioning recognizes the different scales and compensates for them (regular AutoCAD dimensions do not recognize scale areas) by automatically manipulating the DIMLFAC system variable. If you change the DIMLFAC variable manually, especially if you assign different values for this system variable at different places in the same drawing, AutoCAD Mechanical toolset has problems measuring and displaying the correct dimension value. To ensure that AutoCAD Mechanical toolset retains the ability to divide model space into areas having different scale values, we recommend that you do not manually change the DIMLFAC system variable.
If you save a drawing to a pre AutoCAD Mechanical 2009 version, the drawing loses its capability to honor DIMLFAC. When you open such a drawing in the current version of AutoCAD Mechanical toolset, you must enable the ability to honor DIMLFAC, again, using the Dimension Setting dialog box.