AutoCAD MEP 2008 is not backwards compatible

AutoCAD MEP 2008 and AutoCAD Architecture 2008 is not backwards compatible with older versions of ABS and ADT. When you perform a save as, and save back to an older version, that only saves AutoCAD objects, and not MEP or Architecture objects. The 2008 objects will give errors when opened in 2006 even after the save as was performed.

When you perform an Export To Autocad command, it breaks all of the 2008 MEP objects down to 3D solids and there will no longer be MEP or Architectural objects. Now AutoCAD and older releases of AutoCAD MEP can read them without getting errors, but the drawing no longer has the intelligence or data attached to the drawing.

Object enablers only work for programs of the same version, of different verticals such as Architecture, Civil or plain AutoCAD.

If you install AutoCAD MEP 2008 or AutoCAD Architecture 2008 and open and saved a 2007 ABS/ADT drawing, users of ABS/ADT 2007 will no longer be able to open the drawing without getting ARX errors now. In order not to get the ARX errors in ABS/ADT 2007, the drawing will need to be broken and converted to autocad solids. Because it is not backwards compatible, you will only be able to view the MEP or Architectural objects after an Export to AutoCAD has been done. Door, walls and windows will now be just 3D solids, and not doors, walls and windows.

Vertical programs like Architecture and MEP are not backwards compatible like AutoCAD is. It is a big misconception with our customers and we're trying to educate them on how the drawings behave before they ruin some of their production drawings. I have run into this many times in the past, and have been trying to spread the word. There are ways that older ABS/ADT versions can view the 2008 format drawings, but not in it's original or intended format.