You can use the following variables in your odt template file:

Customer data

{field_company}
{field_street}
{field_zip}
{field_city}

Invoice data

{field_invoice_number}
{created}
{field_invoice_total}

Invoice items

As there are often more than one item in the product list you can repeat parts in your template. Just put the following variables between [!-- BEGIN row.invoiceitems --] and [!-- END row.invoiceitems --]

• [!-- BEGIN row.invoiceitems --]
• {field_invoice_item_position}
• {field_invoice_item_desc}
• {field_invoice_item_qty}
• {field_invoice_item_unit}
• {field_invoice_item_unit_price}
• {field_invoice_item_total}
• [!-- END row.invoiceitems --]

Tax data

• [!-- BEGIN row.invoicetaxes --]
• {field_tax_value}
• {field_taxed_amount}
• {field_tax_amount}
• [!-- END row.invoicetaxes --]