Layers, not guesses. A DXF's own layer names suggest what each layer is (A-WALL, RACKING, CONVEYOR…) — you confirm or change it; nothing is classified behind your back. Closed shapes on a block layer become blocks at the height you set for that kind of thing; walls and flow paths are lines. The scale comes from the DXF's units or from a width you give; the preview shows the ratio and the real footprint. Blocks lift off their pockets so a racking layer can be swapped for the proposed one. Features finer than a printer can make at the model's scale are widened or counted out, and you're told.