When you convert DWG files to a format compatible with a previous version, current release information is stripped from objects.
Because converting a drawing to an earlier release format may cause some data loss, it is recommended to assign a different file name to avoid overwriting the current drawing file.
Dynamic constraints created in AutoCAD 2010-based products do not display in DWG TrueView.
Associative dimensions created in AutoCAD 2002-based products or later generally maintain their associativity when converted to a previous release and then reopened in the current release of an AutoCAD-based product.
The following dimension enhancements do not lose visual fidelity in previous releases if they are not edited:
You can specify that annotative objects maintain visual fidelity when they are viewed in AutoCAD 2007-based products and earlier releases in the Modify Conversion Setup dialog box.
Annotative objects may have multiple scale representations. When visual fidelity is on, annotative objects are decomposed and scale representations are saved to separate layers. These layers are named based on their original layer and appended with a number.
When visual fidelity for annotative objects is not selected, a single model space representation is displayed on the Model tab. Depending on a setting when the drawing was saved, additional annotation objects might be displayed on the Model tab, and additional objects might be displayed in paper space viewports at different sizes than in AutoCAD 2008-based products and later releases.
In an AutoCAD 2008-based drawing, when an annotative block does not have its paper orientation set to match the layout, and the block contains multiline attributes that are based on a text style that is not set to match the orientation of the layout, the attributes might shift positions when the drawing is opened in an AutoCAD 2007-based product or an earlier release.
If you convert an AutoCAD 2008-based drawing containing layer property overrides, the overrides are not visible in previous releases. The property override settings are retained when the drawing is saved in a previous release, and are visible again when the drawing is opened in an AutoCAD 2008-based product.
For previous releases of AutoCAD-based products, if the VISRETAIN system variable was set to 0 when the drawing was saved, xref layers containing viewport property overrides are not retained when opened in DWG TrueView.
If you open an AutoCAD 2008-based drawing in a previous release, property overrides might display in a thumbnail image. When the drawing is saved with a layout tab, and then opened in the previous release, those property overrides do not display.
Some of the paragraph spacing and paragraph line spacing options are not supported when an AutoCAD 2008 multiline text object is opened in AutoCAD 2007 and earlier releases.
The following multiline text formatting features have no visual fidelity in previous releases:
The following multiline text formatting features have some visual fidelity in previous releases (when it’s possible to add white spaces or replace text with white spaces):
Multiline text with new formatting that is edited and saved in previous releases loses the new formatting when reopened in AutoCAD 2008-based products.
Editing AutoCAD 2008 tables in previous releases removes AutoCAD 2008 table formatting. Also, AutoCAD 2008 table cells with long block and text strings may extend outside of cell borders when opened in previous releases.
For tables that were created with the Data Extraction wizard in AutoCAD 2008-based products, you can’t edit or update the extracted data in previous releases.
AutoCAD 2008-based products introduced new procedural maps for materials and luminance. Drawings created earlier than AutoCAD 2007 that contain materials need to be converted. AutoCAD 2008 can automatically convert old materials to the AutoCAD 2008 format. However, there are some fidelity issues when saving back to previous versions of AutoCAD.
AutoCAD 2008-based products provide two options for lighting: standard (generic) lighting and photometric lighting. Previous versions offered only standard (generic) lighting. There is no explicit conversion required for lights from AutoCAD 2007 to AutoCAD 2008. Drawings from AutoCAD 2007 open by default in AutoCAD 2008 in the standard (generic) lighting workflow. The additional photometric properties available in AutoCAD 2008 are available as soon as the photometric lighting workflow is enabled in the drawing.
There is a conversion process required for drawings with lighting prior to AutoCAD 2007. AutoCAD-based products include a system variable, 3DCONVERSIONMODE, to automatically convert drawings with lighting from previous versions to the AutoCAD 2007 and AutoCAD 2008 lighting format.
Other lighting fidelity issues include
In DWG TrueView, ACA (formerly called ADT) custom objects are not upgraded when converting the drawing containing them to a different drawing format. This is highly desirable.
In contrast, when the ACA Object Enabler is present in AutoCAD-based products, all ACA objects are upgraded to the latest ACA format. This can present problems when AutoCAD users on the latest version collaborate with ACA users that are several releases behind. AutoCAD users can open the ACA file and save it to the AutoCAD 2004 format used by the previous ACA version, but now the ACA objects are changed to the AutoCAD 2008 versions. When these upgraded ACA objects are encountered in ACA, they are treated as proxy objects.
Converting a drawing to AutoCAD 2007 format is subject to the following limitations:
Converting a drawing to AutoCAD 2004 format is subject to the following limitations:
Converting a drawing to AutoCAD 2000 format is subject to the following limitations:
Converting a drawing in AutoCAD Release 14/AutoCAD LT 98/AutoCAD LT 97 format is subject to the following limitations: