The basis of your model in 3ds Max is the geometry of the objects, blocks, and other entities that are transferred through the file linking functionality. In many cases, these objects behave just like the editable meshes and splines you create in 3ds Max. But because the link to the source drawing plays such a central role in your workflow, 3ds Max has special rules and tools for handling linked AutoCAD geometry.
When you are working with linked objects and blocks from AutoCAD, you will find that these are composed as groups of related objects in 3ds Max. These groups are organized hierarchically below a 3ds MaxVIZBlock object. VIZBlocks are special objects created by the file linking functionality that are used to contain other file linked objects in a group. VIZBlocks don't contain any geometry directly, so for example it is meaningless to apply modifiers to them. However, they do reference the components below them so that transforms applied to a VIZBlock will be applied to all the component objects it contains.
AutoCAD blocks in 3ds Max are treated similarly to AutoCAD objects, though the rules for propagation of transforms are slightly different to mirror the behavior of blocks in AutoCAD.
You can move, rotate, or scale linked AutoCAD objects in 3ds Max, and these transformations will remain intact even after the linked AutoCAD drawing has been reloaded. But you can choose to eliminate the transforms on an object-by-object basis using the Reset Position function, available on the Modifier panel.
Many operations that are allowed on mesh, spline, or shape objects in 3ds Max are not allowed on linked AutoCAD geometry, and other operations behave differently.
