1. block only saves the information of the graphic object once, and only records the name, insertion point, angle and proportion after each insertion. Therefore, if the block is very complex, the file that uses the block is much smaller than the file that uses the copy.
Since the name is recorded, it is convenient for you to change it. Just redefine the block. All blocks inserted with this name have changed. This is a block update.
3. Tools such as Design Center can be used for other documents.
Blanking refers to hiding hidden lines in 3D solid or surface objects.