On this tab, you can enter general information about this customer order adjustment: the customer, contract, entity, customer order which is the basis for the adjustment.
If you are manually creating this adjustment, make sure that original order is selected in the Basis field. Notice that only order with the In Progress status can be adjusted.
The required fields are: Company, Contract, Entity, and Basis. 
The "Customer Order Adjustment (create)" form. The Main tab
In the Company field, select a customer, an individual or legal entity, for whose order this adjustment is created. Select it from the Companies list.
The Contract field is populated automatically with the default contract of the selected company. If necessary, you can select another contract or create a new one.
<Auto> in the Number field indicates that a number for this document is assigned automatically when you save the document. The From field is populated automatically with the current business date. You can select another date, if necessary.
In the Entity field, select the legal entity of your company which is responsible for sales. The Entity field is available if the Multi-Company Accounting option is selected on the Administration > Settings > General Settings form. The default entity entity for all users can be selected on the Accounting >Master Data > Entities form. Also, you can specify your personal default entity, for details refer to Personal Settings.
The Basis field is filled automatically, if the adjustment to customer order has been generated based on the order. If needed, you can manually select the basis document from the list of customer documents (for this, click Show all from the drop-down list). Once the basis order is selected, click the Fill in ( 
) button to copy the data to this order. If, after you edited the adjustment, you want to cancel the edits, click the Fill in button – the details from the basis document will be copied to the adjustment.
In the Comment text box, you can enter any additional information about this order.
The currency of the customer order adjustment is defined according to the selected customer contract. To select other currency, select another contract, or create a new one, if necessary. To learn more about contracts, see Company Contracts.
Notice the hyperlink below the Basis field – AED Wholesale Price VAT Applied*Prices Include VAT* on the screenshot above (can be different in your document). By clicking the hyperlink, you can open the Prices and Currency dialog box and change the settings related to prices, discounts, and taxes applicable to the customer order adjustment. For more details, refer to The Prices and Currency dialog box.
The document totals and other information
At the bottom of the form, you can view who created the document and the current status of the document, which can be one of the following:
...
The VAT (Original) and VAT fields show the tax amounts applicable to the original order and to the adjusted order, respectively.
The Total Due (Original) and Total Due fields show the amounts due by customer according to the original order and adjusted order, respectively.
The Adjustment Amount field shows the difference between these total amounts.
The toolbar buttons
After filling out the tab, click the Save button to save your work. After filling out all the tabs, click Post to save and post the document without closing it or Post and close to save, post, and close the document. For other button descriptions, see Document Toolbar.
Click the Consolidated Analysis by Order link above the toolbar to run this report for the customer order being adjusted.