(This item pertains to the check boxes on the General tab of the Setup Options dialog box. You can open it through the F5 key or through the Edit | Preferences | Setup menu option.)
If this check box is selected, new features inserted into the measurement routine will use the probe tip's vector as the default ClearanceCube start face and end face. Otherwise, the ClearanceCube start face or end face is determined by the feature's vector.