Sometimes you may want to incorporate a new page into a sub-wrapped area like the member home or the moderator control panel. In the past, you might've done that by linking to the new page as profile.php?TID=x to make it appear as part of the member home with the member home menu present. This is problematic if you're trying to incorporate a standard template though, like the help section. If you wanted to make the help section part of the member home, you might've decided to just copy the member home subwrapper content directly into the help templates -- making your site hard to maintain.

Now there's a solution:
<!-- usesubwrapper=homesubwrapper.tpl -->

This works the same as the long-existing <!-- usewrapper=customwrapper.tpl --> syntax that was used for defining a custom wrapper inside the template instead of inside the URL. Now you can do it with subwrappers too. Just put <!-- usesubwrapper=homesubwrapper.tpl --> anywhere inside a template and that template will become part of the member home area.