If you need to specify the order of line items on an invoice, simply add the extra information shown below in red.
Lower numbers will appear first on the invoice.
<line_items type="array">
<line_item>
<code>1-PKE </code>
<description>Palm Kernal </description>
<requested_quantity>12000.00</requested_quantity>
<actual_quantity>12000.00</actual_quantity>
<order>1</order>
</line_item>
<line_item>
<code>2-TAP </code>
<description>Tapioca </description>
<requested_quantity>18000.00</requested_quantity>
<actual_quantity>18000.00</actual_quantity>
<order>2</order>
</line_item>
</line_items>