product url

I notice that when i export products, the csv contains a field "product url". however, this fiend is empty.

after checking the table in the database, i see it is empty there also...why?

reason for asking is that that info is needed to create product data feeds for cpc sites such as shopzilla, and nextag, so having this in the hikashop export would greatly assist in creating the csv's for these sites.

thanks