DespatchLineReference and ReceiptLineReference in GoodsItem

For GoodsItems we need a proper reference to the despatch line it belongs to. GoodsItem has a InvoiceLine that has both, but often the invoice is not issued when the GoodsItem is described. In Peppol we have agreed to allign the GoodsItem ID with the Depatch Line, but a more explicit reference would be preferable.