OODO 14 Qweb XML report needs a small change

I have a simple custom module, wich creates a report for us. On the report it shows now all the product also the service products and we do not want that. The report should only show stockable products.
The change can also be made on the category because whe have our service products in a differtent category.

So we would like the report to be modified to show only a certain catgory or only stockable products.

Sample of orderline:
<t t-if="len(o.order_line)&gt;0">
<span id="t1f_1_m" class="t s4"><strong><t t-esc="int(o.order_line[0].product_uom_qty)"/></strong></span>
<span id="t1e_1_m" class="t s4"><strong><t t-esc="o.order_line[0].product_id.display_name[:47]"/></strong></span>
<span id="t1g_1_m" class="t s4"><strong><t t-esc="o.order_line[0].product_packaging.name or ''"/></strong><strong> / </strong><strong><t t-esc="o.order_line[0].product_packaging.qty or ''"/></strong></span>
<span id="t1h_1_m" class="t s4"><strong><t t-esc="o.order_line[0].product_id.categ_id.name or ''"/></strong></span>
</t>

Greets,

Giel van Maarseveen