Probably it "seems to work" except for problems that may or may not appear related because this test is asking "does my parent have a db:footnote child?", which is true for footnotes but also for siblings of footnotes. "../db:footnote" is short for "parent::node()/child::db:footnote". This isn't quite the same as "am I a db:footnote", but it will be true for all db:footnotes.