FYI: Here is what help has about it.
Access Methods
Command entry: -EXPORTTOAUTOCAD or AECTOACAD
Summary
You can create a new version of a drawing file with all proxy AEC objects exploded into basic objects. The new version of the drawing loses the intelligence of the custom AEC objects, but the resulting basic objects can be displayed and accessed in earlier product versions when object enablers are not available.
This command is used with drawings created in AutoCAD Architecture and previous releases.
List of Prompts
The following prompts are displayed.
Export options [Format/Bind/bind Type/Maintain/Prefix/Suffix/?] <Enter for filename>: Enter an option or press Enter to specify a file name
Enter for Filename
Creates a new drawing file with the specified name.
Format
Determines the drawing file format for the resulting drawing file.
Bind
Determines how xrefs are treated when creating the new drawing.
YesBinds all xrefs to the drawing. Layers and other xref-dependent named objects are merged into the new drawing.
Maintains the xrefs as links to other drawings.
Bind Type
Determines how xref-dependent objects are treated when the Bind option is turned on.
BindMaintains the names of layers and other xref-dependent objects when binding xrefs.
Merges the names of xref-dependent objects into the new drawing without including the original file name.
Maintain
Determines how blocks within custom AEC objects are treated.
YesExplodes all block instances within custom AEC objects into basic objects. The resulting basic objects revert to their original properties rather than the properties of the block definitions.
Does not explode any block instances within custom AEC objects. The properties of the block instances are determined in the usual way, depending on how the objects in the blocks were created and the property settings of the layers on which the blocks are inserted.
Prefix
Specifies the prefix to be added to the current drawing file name.
Suffix
Specifies the suffix to be added to the current drawing file name.
?
List Settings
Lists the current settings for the command.