Release 9.3
Last modified April 24, 2009
About saving a 3D document
Saving a 3D document allows you to preserve your work. A 3D document contains information about paths to your data and the 3D view's properties and layers. When you open an existing 3D document, it will appear as it did when you saved it. ArcGlobe documents have a .3dd extension, and ArcScene documents have a .sxd extension.
You can save 3D documents so you can open and work with them in previous versions of ArcGIS. This makes it easy to share those files with other ArcGlobe or ArcScene users who have not yet upgraded to ArcGIS 9.3.
Saving a 3D document to a previous version of ArcGIS
At ArcGIS 9.3, you can save ArcGlobe documents so they can be opened and used in the ArcGIS 9.0/9.1 versions of ArcGlobe. ArcScene documents can be saved to ArcGIS9.2, 9.0/9.1 or ArcGIS 8.3. All ArcGIS 9.1 documents are directly compatible with ArcGIS 9.0, so there is no need to save them separately for use in ArcGIS 9.1.
Saving 3D documents to a previous version of ArcGIS is similar to saving map documents to a previous version. When you save a 3D document to a previous version of the software, you are only saving that .3dd or .sxd file to the previous version, not the data referenced in it. The source data referenced in the .3dd or .sxd document is unchanged. In addition, older versions of the software won't be able to support some of the new functionality and properties that were added at ArcGIS 9. For example, any 3D symbols will be converted to 2D symbols when an ArcScene document is saved to the ArcGIS 8.3 version.
You can also save the layers in your 3D documents to previous versions of ArcGIS.
Learn more about saving to previous versions of ArcGIS
How to save a 3D document
Saving a 3D document
Saving a 3D document to a previous version of ArcGIS
http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=Saving_a_3D_document