What does the new feature do?

I'm wondering what this does, I noticed it showed up the most recent update to this plugin. I use custompress and haven't noticed it changing or modifying any of the content that i've populated my posts with. I'm using the default theme that comes with directory though, so I wasn't sure if that has an effect. There's no explanation in the documentation either.

Display Custom Fields as: Structure of the custom fields block/li/ul