Dynamic Constraints

Dynamic constraints created in AutoCAD 2010-based products do not display in DWG
TrueView.

Associativity in Dimensions

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.

Visual Fidelity of Dimensions

The following dimension enhancements do not lose visual fidelity in previous releases
if they are not edited:

• Dimension breaks
• Jogged linear dimensions
• Inspection dimensions
• Angular dimensions that are dimensioned using the quadrant option
• Arc extension lines for radial and diameter dimensions

Visual Fidelity for Annotative Objects

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.

Annotative Blocks

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.

Layer Property Overrides

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.

Multiline Text Objects

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:

• Paragraphs with justified alignment
• Paragraphs with distributed alignment
• Fields that wrap across columns
• Fields that wrap across lines that have new paragraph alignments
• Paragraphs with non-default alignments in multiline text without left object-level
  justification

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):

• Paragraphs with non-default alignments (other than justified or distributed) in multiline
  text that has left object-level justification
• Paragraphs with tabs using tab alignments (center, right, or decimal alignment applied)
• Paragraphs with line spacing that can be approximated with “tallâ€‌ 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.

Tables and Data Extraction

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.

Materials (Rendering)

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.

• Procedural maps Checker, Noise, Speckle, Tiles, and Waves are not available in AutoCAD
  ۲۰۰۷ and previous releases. They do not appear when an AutoCAD 2008 drawing is opened
  in AutoCAD 2007. Marble and Wood are available but the material might show some variation.

• The behavior of the Opacity map channel under the Realistic material type has been
  corrected in AutoCAD 2008 based products. In AutoCAD 2008, the Opacity map channel
  behaves like a transparency map, where white is transparent and black is opaque (this
  was how it behaved prior to AutoCAD 2007). In AutoCAD 2007, white represented opaque
  areas and black represented transparent areas.
• The spherical map rotation is different in AutoCAD 2008-based products. When you open
  a drawing prior to AutoCAD 2008, the seam for the map is towards the +Y axis. In AutoCAD
  ۲۰۰۸, it is towards the +X axis.

Lighting (Rendering)

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
۲۰۰۸ 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
۲۰۰۷. AutoCAD-based products include a system variable, 3DCONVERSIONMODE, to automatically
convert drawings with lighting from previous versions to the AutoCAD 2007 and AutoCAD
۲۰۰۸ lighting format.

Other lighting fidelity issues include

• Lights in blocks. Lights in blocks created in AutoCAD 2008 do not always display in AutoCAD 2007.
• Texture illumination. In AutoCAD 2007 and earlier releases, you cannot add lighting to textures as in AutoCAD
  ۲۰۰۸.
• Ground Shadows. The intensity of ground shadows in AutoCAD 2008 depends on the brightness of the
  light and angle of incidence.

AutoCAD Architecture (ACA) Custom Objects

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
۲۰۰۸ versions. When these upgraded ACA objects are encountered in ACA, they are treated
as proxy objects.

Additional limitations of Saving to Earlier Versions

Converting a drawing to AutoCAD 2007 format is subject to the following limitations:

• DGN underlays do not display in releases prior to AutoCAD 2008.
• Multileaders display as proxy objects in releases prior to AutoCAD 2008.

Converting a drawing to AutoCAD 2004 format is subject to the following limitations:

• Dynamic block geometry can be redefined independent of the block’s dynamic elements,
  and the geometry in the block reference is not updated when the drawing is opened
  in a product based on AutoCAD 2007 or later.

Converting a drawing to AutoCAD 2000 format is subject to the following limitations:

• File size can increase.
• Encryption and digital signatures are not preserved.

Converting a drawing in AutoCAD Release 14/AutoCAD LT 98/AutoCAD LT 97 format is subject
to the following limitations:

• Hyperlinks are converted to AutoCAD Release 14 attached URLs.
• Database links and freestanding labels are converted to AutoCAD Release 14 links and
  displayable attributes.
• Database attached labels are converted to multiline text and leader objects, and their
  link information is not available. Attached labels are restored if you open the drawing
  in AutoCAD 2000 or later.
• Arc length and jogged dimension objects might not retain their original color in AutoCAD
  Release 14.
• DWG TrueView does not convert of pen-width settings to lineweights.