Thank you for adding your array structure. This should work fine with OpenTBS.
So assuming you have something like:
<w:body>[customers;block=w:body;]
Customer Name: [customers.name;]
</w:body>
In order to get nested information from the customers array you would do:
<w:body>[customers;block=w:body;sub1=itemsinfo]
Customer Name: [customers.name;]
Customer Items:
<w:table>
<w:tr>
<w:td>[customers_sub1.itemname;block=w:td;]</w:td>
</w:tr>
</w:table>
</w:body>
This would cause the w:td to repeat for each item in the itemsinfo array - probably not your desired behavior but hopefully enough to get you going again. The manual is quite helpful, but it unfortunately makes more sense after you already understand...