MinOccurs 1 is rather useless. It can help identify WSDL requirements but tells you nothing about application specific requirements.
You should go for the human readable documentation: https://api.e-conomic.com/secure/api1/EconomicWebService.asmx?op=CurrentInvoiceLine_CreateFromData
XML structure as described on above link.
<Handle><Id>int</Id><Number>int</Number></Handle><Id>int</Id><Number>int</Number><InvoiceHandle><Id>int</Id></InvoiceHandle><Description>string</Description><DeliveryDate>dateTime</DeliveryDate><UnitHandle><Number>int</Number></UnitHandle><ProductHandle><Number>string</Number></ProductHandle><Quantity>decimal</Quantity><UnitNetPrice>decimal</UnitNetPrice><DiscountAsPercent>decimal</DiscountAsPercent><UnitCostPrice>decimal</UnitCostPrice><TotalNetAmount>decimal</TotalNetAmount><TotalMargin>decimal</TotalMargin><MarginAsPercent>decimal</MarginAsPercent><DepartmentHandle><Number>int</Number></DepartmentHandle><DistributionKeyHandle><Number>int</Number></DistributionKeyHandle><InventoryLocationHandle><Number>int</Number></InventoryLocationHandle>
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