Does anyone know or have any links to information on how DimXpert decides if a surface is unconstrained, underconstrained, constrained, or overconstrained? My experience is that the calculation it does is unpredictable and often incorrect.  Some examples:

1. Often adding a single constraint to an under-constrained surface will make it over-constrained.
2. Picture two holes on the top surface of a box with all of the sides constrained. Let the X-Y plane be the top of the box. Insert a +/- dimension for the x-distance of one hole from the closest side perpendicular to the x-axis. Insert another +/- dimension for the x-distance between the two holes. Now DimXpert reports both holes as overconstrained. Sometimes if you set the +/- dimension to be from the 2nd hole to its outer face, then things are OK even if there is a constraint on the total width.
3. Sometimes you get a message saying "Added tolerance has overconstrained the part" when you add a datum.
4. Adding a hole pattern on one face causes another face to go from fully constrained to underconstrained.
5. Many, many, many times I end up with 1 item overconstrained and 1 item underconstrained.
6. Sometimes Ctrl-Q or closing SW and re-opening it will resolve the 1-item-over-and-1-item-under problem mentioned above.
7. There is zero documentation available outside of the help file that is little more than just a list of what the property managers do.

I would like to do a tolanalyst study, but I can't get DimXpert to constrain things properly.

I suspect that once you have a datum reference frame that when you add another datum, DimXpert lets the oldest datum float. If so, this is useless for any part that needs multiple DRFs.