Saving in the STEP format preserves the assembly tree structure, (not part features), but I'm not sure if you can get MDT4 to read MDT5 STEP files. To make STEP files, you need the Data Exchange module add-on which also handles VDAFS format. With standard settings, I could not read MDT5 STEP files in MDT4, but I believe this depends on the ACIS version. If you change the ACISOUTVER command in MDT5 to create the files with the same ACIS version as MDT4, you should be able to read the files. Has anyone else tried this?
Ron Morin
GSFE, Inc.
www.gsfeng.com