Confluence 5.7 has reached end of life
Check out the [latest version] of the documentation
-BADSPACE you will get only content which is not in the BADSPACE.+GOODSPACE you will get only content in GOODSPACE. (Note that this is not particularly useful, because each content item belongs to one space only. If you put a plus sign next to one space key and list other space keys too, the other space keys will be ignored.)