More flexible editing in index cards

I would like to use spacing in index cards, blank lines between items. But it seems I can’t do that. Any use of the return key inserts a new card. Is there a way to insert a blank line?

Hold down the Alt (sometimes labelled “Option”) key while hitting Return.

This works in the outliner, too, and in pretty much any control in most OS X applications - it’s a very useful in Find panels etc, for instance.
All the best,