AutoFormat.RemoveEmpty.Predicate TYPE: hash VERSION: 4.7.0 DEFAULT: array('colgroup' => array(), 'th' => array(), 'td' => array(), 'iframe' => array('src')) --DESCRIPTION--
  Given that an element has no contents, it will be removed by default, unless
  this predicate dictates otherwise.  The predicate can either be an associative
  map from tag name to list of attributes that must be present for the element
  to be considered preserved: thus, the default always preserves colgroup,
  th and td, and also iframe if it
  has a src.