Without a PDM software package, you are limited to "best practices" techniques amoung your engineers, designers and CAD operators.
I know many companies try to use the same methods to control thier 3d files as they have with thier 2d files, only to find out that it will only work for a short period of time (1-2 years at best). "Happy the Hare at morning for she is ignorant to the Hunter's waking thoughts."
Use a PDM system if you can. But with that said, “To manually enter the revision on the drawing”. Place $PRPSHEET:"REVISION” in your drawing template that everyone is using. In the Custom property of your model template or model have a Name: Revision. Now when you change the models Revision, the drawings Revision will match. Please control your drawing revision from the models. If these directions are not complete enough, let me know I will clarify in more detail. Bradley
