Magento: Building a store URL in CMS-syntax, using a variable

I am building an e-mail template. I want to build a URL like this开发者_开发问答:

http://store.com/path/to/page?shipmentid=123

This code builds the correct URL:

{{store url='path/to/page' _query_shipmentid=123}}

But the 123 part should be dynamic. I need it to pull from this variable:

{{var shipment.id}}

Is this even possible? I'm looking for something like this:

{{store url='path/to/page' _query_shipmentid=shipment.id}}

Use $ prefix to let Magento know that it is variable. This code should work:

{{store url='path/to/page' _query_shipmentid=$shipment.getId()}}