This means that a route's grade may vary significantly from the grade it receives as a regular rock route. The next symbol listed is the commitment grade. This number consists of how long and involved the approach is along with the inherent dangers in doing the climb. Note that the commitment grade for ice varies somewhat from the commitment grade for Alpine climbs, although the concept is the same. These represent the type of ice that you may be facing.
Most mixed routes are also thin.
Fragile routes are routes that may collapse upon climbing. Some climbs also have one to three stars associated with them. These represent how enjoyable the climb is and are by nature fairly subjective. They do, however, help narrow down which climbs are the most enjoyable to do. Please note that the very nature of waterfall ice implies that climbs are far more dynamic than rock climbs.