By BOM I mean Bill of Materials which is organized in a hierarchical structure ( Tree View)
This data I will have in excel with data with columns
ID, Name, Level, Quantity
001, Assembly, 1, 1
002, Sub Assy, 2, 1
003, Part 1, 3, 1
004, Part 2, 3, 1
Level Column will define the structure of BOM.
Next time edit your original question instead of answering your own question. Keeps the forum tidy.
Now on topic. If you create a domain model in Mendix you could use the Excel importer to get the data inside Mendix. I would advise to not directly import it in the main objects but create import objects that you can then copy over to the objects you want to use. This way you have a lot more control on the importdata so you can transform attributes if needed or do validation checks.