Model length units are set at the time of geometry import. Once defined they cannot
be altered. For most CAD documents, embedded model units are used. Since STL files
are by definition unitless, a dialog will prompt for guidance (millimeter,
centimeter, meter, inch or foot). Bounding box dimensions are displayed to aid the
user in selecting the appropriate value.
Note: Special considerations for model
length units.
To learn how to set default units, see the Set Default Input/Output Units topic.