AbleCommerce Shopping Cart Software

I see in code there is the ability to pass a query string param for "theme" such as to preview a theme in development without affecting the production store? Is this documented anywhere so I can learn how to use it? I haven't tried it yet but I assume just pass in the theme name via a URL.

You need to go to Administration > Website > Manage Themes page. From action area in front of theme name that you want to preview use preview button (Magnifying Glass Icon) .