Here's exactly what the lead developer had to say about your question:
I had to do research on this. As of present it is not supported by any of the major browsers.
https://www.w3schools.com/cssref/css3_pr_target-name.aspThe new window is frowned down upon in web development. Specifically with the subscribe links, if the application is on a platform that supports them, then the new window will load a blank page then run the application itself, which may leave a blank new window artifact that then confuses the user at a later time. They are welcome though to use JavaScript, or more specifically, JQuery to set target events for the links. We use common CSS classes for the links and it is easy to create events with jQuery for them if they so desire.