Note that the AutoCAD Map 3D Object Data reader directives list defaults that will produce the best generic result to any non-AutoCAD destination format, resulting in the best presentation at the cost of some of the original AutoCAD types being lost. For example, blocks and dimensions will be resolved into their component parts.
If an AutoCAD-to-AutoCAD translation is desired, the following set of options should be used for best preservation of the original drawing.
STORE_BULGE_INFO = YES
STORE_SPLINE_DEFS = YES
RESOLVE_BLOCKS = NO
RESOLVE_DIMENSIONS = NO
RESOLVE_ENTIY_COLOR = NO
VISIBLE_ATTRIBUTES_AS_TEXT = NO
IGNORE_UCS = YES
PRESERVE_COMPLEX_HATCHES = YES
IGNORE_HIDDEN_LAYERS = NO
EVALUATE_MLINE_GEOM = NO
OD_READING_MODE = od_mode_raw or od_mode_classic
These are also noted on each individual directive description.