What do you mean by net postings?

Usually, when a transaction is posted, for example, a vendor invoice (document type: KR), the system posts the Gross amount with the tax and discount included. However, SAP provides you the option of posting these items as Net. In this case, the posting excludes tax or discounts. Remember to use the special document type KN. (Similarly, you will use the document type DN for customer invoice-Net compared to the normal invoice postings for the customer using the document type DR.) For using this net method of posting you should have activated the required settings in the customization.