Hi @matze32,
That’s not recommended because even if the M_Product_ProductType is a list like any other list, each of those items has special meaning in java code and the product is handled differently based on those types.
For example, a product of type Service does not need to be received and in accounting, it will be booked directly on expense instead of increasing the product asset account.
If you want to categorize your products, you can use the product category.
Or if you want to go deeper in customization (but really depends on your actual needs) you can introduce a new field.
Best regards,
Teo