Edit a booking and its line items

Owners, admins, accountants and bookkeepers can edit a booking; the tax advisor and the client roles can only read it. A booking can be edited only while it is not Posted, not exported and its month is open. The booking of an issued invoice is read only: its corrections go through the invoice (see Why a booking, invoice or month is locked).
Open Bookings and click the booking. The panel shows the fields beside the pages of the document. Change Supplier, Label, Amount, Currency, VAT rate, VAT amount, Tax code, Type, Document type, Document date, Posting date, Category, Project, Description, the invoice number and the supplier's VAT ID and country, then choose Save; Saved confirms it. You can also put the cursor in a field and click a word on the document page to fill it.
Document date is the date on the voucher; Posting date decides the month the booking counts in for the books, the reports, the month lock and the DATEV export, and starts as the document date. Changing it leaves the document date as it is. A posting date in a closed month is refused. It does not move the VAT return period.
The app refuses impossible values: an Amount of 0 or above 1,000,000,000.00, a VAT rate outside 0 to 100 percent, a VAT amount larger than the gross amount, a Document date before 1 January 2000 or more than a year ahead, and a booking without a Label once it had one. Save stays disabled while an amount or date is not valid. Changing Type switches the tax code to the other side; if the Category no longer fits the direction, it is removed and a notice asks you to pick another.
FX rate and Converted appear for a foreign currency and are read only. For a booking with several VAT rates the panel shows Revenue per VAT rate instead of one category and rate, and does not edit them.
Line items lists the lines of the document. Change a line and use its save icon; the line is stored at once, not with Save. The trash icon asks for Yes, delete. To add a line, fill the empty row at the bottom (description is required) and choose Add; each line has Qty, Unit price, Total, VAT % and SKU. Quantity times unit price must equal the total (1 cent per unit of tolerance), otherwise the line is refused. A notice warns when the lines do not add up to the booking's net amount; it does not change the booking. Once the booking is posted or exported, the lines are shown read only.
Payment terms holds Due date, Payable within (days), Early payment discount (%) and Discount within (days). The discount and its days belong together: fill both or leave both empty, otherwise Save stays disabled. A due date before the document date gives a warning.
If someone else saved the booking first, the app loads their version and says so: check it and save again. When the booking is ready use Mark reviewed, then Post booking and confirm with Post it for good (unchangeable afterwards); unsaved edits are saved first, open blockers refuse both steps, and posting needs owner, admin or accountant. A posted booking is corrected with Reverse (see Reverse a booking (Storno)).