Its an effort to costumize the drawings
if you insert a BOM in a part, drawing or assembly, you can modify it in the way you want.
Then, when you right click in the table, there is an option in the menu that is Save...
If you click it, it appears a window where you have to say where to save and the extension you want for your table. If you don't touch the extension it is format of BOM table, so you are saving the format not the list.
I hope it is what you were searching,
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