training and fencing applications often employ: the jian, a straight double-edged sword, practiced as taijijian; the dao, a heavier curved saber, sometimes called a broadsword; the tieshan, a folding fan, also called shan and practiced as taijishan; the gun, a 2 m long wooden staff and practiced as taijigun; the qiang, a 2 m long spear or a 4 m long lance. More exotic weapons include: the large dadao and podao sabres; the ji, or halberd; the cane; the sheng biao, or rope dart; the sanjiegun, or three sectional staff; the feng huo lun, or wind and fire wheels; the lasso; the whip, chain whip and steel whip. Attire and ranking Some martial arts require students to wear a uniform during practice. In general, Tai Chi does not specify a uniform, although teachers often advocate loose, comfortable clothing and flat-soled shoes. Modern day practitioners usually wear comfortable, loose T-shirts and trousers made from breathable natural fabrics, that allow for free movement. Despite this, T'ai-chi ch'üan has become synonymous with "t'ai-chi uniforms" or "kung fu uniforms" that usually consist of loose-fitting traditional Chinese styled trousers and a long or short-sleeved shirt, with a Mandarin collar and buttoned with Chinese frog buttons. The long-sleeved variants are referred to as Northern-style uniforms, whilst the short-sleeved, are Southern-style uniforms. The clothing may be all white, all black, black and white, or any other colour, mostly a single solid colour or a combination of two colours: one colour for the garment and another for the binding. They are normally made from natural fabrics such as cotton or silk. They are usually worn by masters and professional practitioners during demonstrations, tournaments and other public exhibitions. Tai chi has no standardized ranking system, except the Chinese Wushu Duan wei exam system run by the Chinese wushu association in Beijing. Most schools do not use belt rankings. Some schools present students with belts depicting rank, similar to dans in Japanese martial arts. A simple uniform element of respect and allegiance to one's teacher and their methods and community, belts also mark hierarchy, skill, and accomplishment. During wushu tournaments, masters and grandmasters often wear "kung fu uniforms" which tend to have no belts. Wearing a belt signifying rank in such a situation would be unusual. Seated tai chi Traditional tai chi was developed for self-defense, but it has evolved to include a graceful form of seated exercise now used