AutoCAD®
Import Options - DWG / DXF 
File
Import
Set AutoCAD Options
Use this form to perform various tasks while importing AutoCAD®
files.
Complete the form as desired.
Pick OK to accept the current selections as the new defaults or Reset to return all selections to their previous defaults.

Auto sew geometry
Closed surface volumes will be sewed (joined) at their mating
edges to form a solid once they have been imported into VX. This
option requires that the imported edges fall within tolerance of each
other.
If importing directly into an existing object or one that is currently active, the default tolerance displayed in the Part Settings Form is used. If importing into a new object (created during the import), the default system tolerance (0.1mm) is used.
Auto activate part
The imported file will be automatically activated for editing (i.e., it will become the active part).
Reduce Data
Imported entities are recalculated to within the tolerance specified below and refitted with a lesser number of control points thus reducing and simplifying the data.
Trim Surface
Trim surfaces will be imported.
These tolerance settings govern the accuracy of resulting imported curves and surfaces. The tolerance values are a factor of the Units value currently set in the Part Settings Form (i.e., Value * Units = Tolerance in Units).
UV Curve
Enter the UV Curve tolerance factor for the resulting imported data. This tolerance applies specifically to the UV space of resulting surfaces and will affect the trim loop boundaries of a trimmed surfaces.
Curve
Enter the Curve tolerance factor for the resulting imported curves.
Surface
Enter the Surface tolerance factor for the resulting imported surfaces.
Model Space, Paper Space
AutoCAD drawings can contain geometry in either model space (3D) or paper space (2D). VX can read either or both spaces in the incoming file. Place a check in each box that applies.
This sets the default directory for locating
files to import of the specified type. Pick the folder icon to select
a path from the Directory Browser. The path will
be added to the Default Directory Field. The Default directory
field only applies to the active session while
VX is running unless it is permanently saved using the Save Settings
button on the Import Form.
More about the Default Directory 
All import/export translators have their own default-directory on their options form. If the default-directory is set, then the Directory Browser will always come up in that directory. If the default-directory is not set, then the file browser will come up in the "last visited" directory.
The last visited directory is not unique. There is one last visited for all import translators and one for all export translators. By default, the value in the Default Directory field is set to '.' which means, use the "last visited" directory. The file icon allows you to browse for a directory which will then be the new default. You can set the Default Directory back to "." by selecting Reset on the form.