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. Ethics The ethics climbers adopt toward their sport are not always steadfast, and they often depend on the venue. The following examples are merely outlines that do not always hold true. Bolting Whether a route should be bolted as a sport climb is often in dispute. In some areas, including some in the United States, if a route cannot be safely climbed with the use of traditional gear, it is generally acceptable to the climbing community to bolt it. In much of the United Kingdom, similar bolting is widely considered unacceptable. Regulations regarding bolting can vary from state to state and between landowners or land managers. Additionally, the method of bolting may often be challenged. Many early sport routes were bolted on lead by the first ascender: a "traditional" approach. One could say that it became "sport" climbing when routes started to get bolted from the top (hanging on a rope). First ascents Sometimes, a newly bolted route is considered "red tagged," and ethics dictate that the person who bolted the route should be the only climber to attempt it until they have made a free ascent (a continuous roped ascent, made using only hands and feet, unaided – yet protected – by the bolts, quickdraws or rope). This is because equipping a new route is an expensive and time-consuming endeavor for the person who finds it. Other times, the bolter will allow the route they developed to become an "open project" that anyone can try. Ascents of reserved routes have led to a number of controversies in the sport climbing world. Chipping, comfortizing, and reinforcing Changing the natural features of rock is often frowned upon, but in many parts of the world it is accepted to some extent. In some areas, "chipping" of the rock with a chisel or similar tool to create a