EU Avoir / Creditnota

Key features Reason-code catalogue (commercial gesture, return of goods, price correction, invoicing error, duplicate, contractual rebate, write-off) with the regional legal labels FR ``avoir`` / BE ``note de credit`` / ``creditnota`` / NL ``creditnota`` and a default VAT-reversal rule per code. Hard linkage to the original posted invoice: copies the legal number, customer, original date and currency, and computes how much of the original is already credited so you never over-credit a document. VAT reversal check: re-summarises tax per rate from the original invoice and verifies the credit note reverses the same bases/rates; flags a mismatch before posting. Per-country legal numbering sequence (separate ``AV`` / ``NC`` / ``CN`` series) and a mandatory legal-mention block on the printed document. Partial / full credit wizard that builds a draft credit note from an invoice, pre-filling reason code, lines and the regional mentions. Credit-note register with credited-ratio, reason and VAT-reversed totals for the period, exportable for the accountant.