Units Tab
The Units tab can be found under CATIA's Tools 
Options General Parameters and Measure.
Under this tab, under the "Units" section, the user can find all units available listed, and the selected unit shown next to the grayed-out Length option.
3DCS follows the CATIA units. The default unit is millimeters. To change the units, simply click the drop-down list at the bottom of the units window and select the desired unit. Your data will automatically be updated throughout the DCS model.
Note: You may select any unit that is offered within the drop-down list.