Save to a previous version of AutoCad ARCHITECTURE?

[floorplanz]

When a drawing is created in AutoCad Architecture 2009, and I try to do a save-as, there are no options for previous versions of AutoCad Architecture, the only options are for previous versions of AutoCad. Why? Or better yet, how do I save as a previous version of AutoCad Architecture?

[Anonymous]

You don't. An Acad file is an Acad file to ACA regardless of being saved in
ACA. Besides, I don't think that ACA's AEC entities travel back to the
previous major version anyway (which from 2009 would be the 2004 format).
It will travel back to 2008 and (with only a few things to watch for) 2007
without problems (as it's an '07 format with a few added tricks from
'08/'09), but not 04-06 or earlier.

[Paullafferty55]

If you go to file - export to autocad - it gives you an option to save back to 2007 , 2004 or 2000