In the United States, the Yosemite Decimal System is used to rate sport climbs. Current grades for sport routes vary between an easy 5.0 to an extremely difficult 5.15d, although the system is open-ended. Past 5.10, letter grades between "a" and "d" are sometimes used for further subdivision (e.g. 5.11a or 5.10d). Pluses and minuses may also be used (e.g. 5.9+ or 5.11–). Originally, the YDS rating was designed to rate the difficulty of the hardest move on a given route. However, modern sport grades often take into account other features such as length and number of difficult moves along the route.