In this workflow, you create blocks to group part geometry together, then attach a Part Reference to each block.
The BOM considers such blocks to be parts and lists them in the BOM dialog box. When you insert an instance of such a block in the drawing area, the BOM automatically increments the quantity of that part
To attach a Part Reference to a block, use the Block option of the AMPARTREF command. If the block has attributes with the same name as the component properties of the Part Reference, AMPARTREF automatically imports the attribute value.
If you create a nested block using “part” blocks, and attach a Part Reference to the nested block, the BOM considers the nested block to be an assembly. In the BOM, the “part” blocks are nested under the “assembly” to which they belong. In this manner you can build a hierarchy of assemblies, subassemblies, and parts within the drawing using the BOM.