How to add a custom parameter in javascript template?

I'm working on the javascript templating system. I successfully created an x-magento-template (see here)

But I still don't understand how magento work with it internaly.

My template looks like that :

<script id="custom-option-select-type-row-template" type="text/x-magento-tmpl">
    <% console.log(data) %>
</script>

And produce this result :

Object { id: "1", option_type_id: -1, select_id: 1, sku: "", price: "" }

The script as the id of an existing template in Magento\Catalog module.

I didn't find in magento code any :

mageTemplate("#custom-option-select-type-row-template");

So, how magento can fill the "data" object and find the template to call ?

I want to be able to add my own parameter in this object.